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    The complete Maple Conference 2024 program is now available online. You can view it HERE.
    Thank you to all those who voted for the "Audience Choice" sessions. The winning topics are listed in the program.

    Registration is still open and free of charge.  

    We hope to see you there!

    Just finished an exciting lecture for undergraduate students on Euler methods for solving ordinary differential equations (ODEs)! 📝 We explored the Euler method and the Improved Euler method (a.k.a. Heun's method) and discussed how these fundamental techniques work for approximating solutions to ODEs.

    To make things practical and hands-on, I demonstrated how to implement both methods using Maple—a fantastic tool for experimenting with numerical methods. Seeing these concepts come to life with visualizations helps understand the pros and cons of each method.

    The Euler method is the simplest numerical approach, where we approximate the solution by stepping along the slope given by the ODE. But there's a catch: using a large step size can lead to large errors that accumulate quickly, causing significant deviation from the real solution.

    Plot Results:

    • With a larger step size (h=0.5h = 0.5h=0.5), the solution tends to drift away significantly from the actual curve.
    • Reducing the step size improves accuracy, but it also means more steps and more computation.

    Next, we discussed the Improved Euler method, which is like Euler's smarter sibling. Instead of blindly following the initial slope, it:

    1. Estimates the slope at the start.
    2. Uses that slope to predict an intermediate value.
    3. Then, it takes another slope at the intermediate point.
    4. Averages these two slopes for a better approximation.

    This technique makes a big difference in accuracy and stability, especially with larger step sizes.

    Plot Results:

    • Using the Improved Euler method, we found that even with a larger step size, the solution is smoother and closer to the true path.
    • The average slope helps mitigate the inaccuracies that arise from only using the beginning point's derivative, effectively reducing the local error.
    • The standard Euler method can produce solutions that oscillate or diverge, especially for larger step sizes.
    • The Improved Euler method follows the actual trend of the solution more faithfully, even with fewer steps. This makes it a more efficient choice for balancing computational effort and accuracy.
    • The Euler method is great for its simplicity but often requires very small step sizes to be accurate, leading to more computational effort.
    • The Improved Euler method—which we implemented and visualized on Maple—proved to be more reliable and accurate, especially for larger step sizes.

    It was amazing to see the students engage with these foundational methods, and implementing them on Maple brought a deeper understanding of numerical analysis and the challenges of solving differential equations.


     


    restart

    with(plots)

    with(DEtools)

    ODE1 := diff(y(x), x) = -2*x*y(x)/(x^2+1)

    diff(y(x), x) = -2*x*y(x)/(x^2+1)

    (1)

    NULL

    We calculate the general solution to the ODE

    NULL

    dsolve(ODE1, y(x))

    y(x) = c__1/(x^2+1)

    (2)

    NULL

    Now let's solve the problem for the following two inital conditions

    y(0) = 2 and y(0) = 1/2

    dsolve({ODE1, y(0) = 2}, y(x))

    y(x) = 2/(x^2+1)

    (3)

    dsolve({ODE1, y(0) = 1/2}, y(x))

    y(x) = 1/(2*x^2+2)

    (4)

    Then, we are going to plot the solutions to the IVP's together with the slope field corresponding to the ODE.

     

    NULLdfieldplot(ODE1, [y(x)], x = -5 .. 5, y = -5 .. 5, color = blue, scaling = constrained, axes = boxed)

     

     

    DEplot(ODE1, y(x), x = -5 .. 5, y = -5 .. 5, [[y(0) = 2], [y(0) = 4]], linecolor = red, color = blue, scaling = constrained, axes = boxed)

     

    Problem 2 (EULER METHOD)

    NULL

    NULL

    ODE2 := diff(y(x), x) = sin(x*y(x))

    diff(y(x), x) = sin(x*y(x))

    (5)

     

     

    dsolve(ODE2, y(x))

    NULL

    Maple returned no output! That means Maple is unable to solve the equation.

    NULL

    If you are curious what steps Maple went through to  find a solution before failing
    to do so, you can ask to see the steps using the command "infolevel". The levels
    of information that you can request range from 0 to 5.

     

    ````

    dsolve(ODE2, y(x))

    soln := dsolve({ODE2, y(0) = 3}, y(x), numeric)

    proc (x_rkf45) local _res, _dat, _vars, _solnproc, _xout, _ndsol, _pars, _n, _i; option `Copyright (c) 2000 by Waterloo Maple Inc. All rights reserved.`; if 1 < nargs then error "invalid input: too many arguments" end if; _EnvDSNumericSaveDigits := Digits; Digits := 15; if _EnvInFsolve = true then _xout := evalf[_EnvDSNumericSaveDigits](x_rkf45) else _xout := evalf(x_rkf45) end if; _dat := Array(1..4, {(1) = proc (_xin) local _xout, _dtbl, _dat, _vmap, _x0, _y0, _val, _dig, _n, _ne, _nd, _nv, _pars, _ini, _par, _i, _j, _k, _src; option `Copyright (c) 2002 by Waterloo Maple Inc. All rights reserved.`; table( [( "complex" ) = false ] ) _xout := _xin; _pars := []; _dtbl := array( 1 .. 4, [( 1 ) = (array( 1 .. 28, [( 1 ) = (datatype = float[8], order = C_order, storage = rectangular), ( 2 ) = (datatype = float[8], order = C_order, storage = rectangular), ( 3 ) = ([0, 0, 0, Array(1..0, 1..2, {}, datatype = float[8], order = C_order)]), ( 4 ) = (Array(1..65, {(1) = 1, (2) = 1, (3) = 0, (4) = 0, (5) = 0, (6) = 0, (7) = 1, (8) = 0, (9) = 0, (10) = 0, (11) = 0, (12) = 0, (13) = 0, (14) = 0, (15) = 0, (16) = 0, (17) = 0, (18) = 21, (19) = 30000, (20) = 0, (21) = 0, (22) = 1, (23) = 4, (24) = 0, (25) = 1, (26) = 15, (27) = 1, (28) = 0, (29) = 1, (30) = 3, (31) = 3, (32) = 0, (33) = 1, (34) = 0, (35) = 0, (36) = 0, (37) = 0, (38) = 0, (39) = 0, (40) = 0, (41) = 0, (42) = 0, (43) = 1, (44) = 0, (45) = 0, (46) = 0, (47) = 0, (48) = 0, (49) = 0, (50) = 50, (51) = 1, (52) = 0, (53) = 0, (54) = 0, (55) = 0, (56) = 0, (57) = 0, (58) = 0, (59) = 10000, (60) = 0, (61) = 1000, (62) = 0, (63) = 0, (64) = -1, (65) = 0}, datatype = integer[8])), ( 5 ) = (Array(1..28, {(1) = .0, (2) = 0.10e-5, (3) = .0, (4) = 0.500001e-14, (5) = .0, (6) = .16290418802201975, (7) = .0, (8) = 0.10e-5, (9) = .0, (10) = .0, (11) = .0, (12) = .0, (13) = 1.0, (14) = .0, (15) = .49999999999999, (16) = .0, (17) = 1.0, (18) = 1.0, (19) = .0, (20) = .0, (21) = 1.0, (22) = 1.0, (23) = .0, (24) = .0, (25) = 0.10e-14, (26) = .0, (27) = .0, (28) = .0}, datatype = float[8], order = C_order)), ( 6 ) = (Array(1..1, {(1) = 3.0}, datatype = float[8], order = C_order)), ( 7 ) = ([Array(1..4, 1..7, {(1, 1) = .0, (1, 2) = .203125, (1, 3) = .3046875, (1, 4) = .75, (1, 5) = .8125, (1, 6) = .40625, (1, 7) = .8125, (2, 1) = 0.6378173828125e-1, (2, 2) = .0, (2, 3) = .279296875, (2, 4) = .27237892150878906, (2, 5) = -0.9686851501464844e-1, (2, 6) = 0.1956939697265625e-1, (2, 7) = .5381584167480469, (3, 1) = 0.31890869140625e-1, (3, 2) = .0, (3, 3) = -.34375, (3, 4) = -.335235595703125, (3, 5) = .2296142578125, (3, 6) = .41748046875, (3, 7) = 11.480712890625, (4, 1) = 0.9710520505905151e-1, (4, 2) = .0, (4, 3) = .40350341796875, (4, 4) = 0.20297467708587646e-1, (4, 5) = -0.6054282188415527e-2, (4, 6) = -0.4770040512084961e-1, (4, 7) = .77858567237854}, datatype = float[8], order = C_order), Array(1..6, 1..6, {(1, 1) = .0, (1, 2) = .0, (1, 3) = .0, (1, 4) = .0, (1, 5) = .0, (1, 6) = 1.0, (2, 1) = .25, (2, 2) = .0, (2, 3) = .0, (2, 4) = .0, (2, 5) = .0, (2, 6) = 1.0, (3, 1) = .1875, (3, 2) = .5625, (3, 3) = .0, (3, 4) = .0, (3, 5) = .0, (3, 6) = 2.0, (4, 1) = .23583984375, (4, 2) = -.87890625, (4, 3) = .890625, (4, 4) = .0, (4, 5) = .0, (4, 6) = .2681884765625, (5, 1) = .1272735595703125, (5, 2) = -.5009765625, (5, 3) = .44921875, (5, 4) = -0.128936767578125e-1, (5, 5) = .0, (5, 6) = 0.626220703125e-1, (6, 1) = -0.927734375e-1, (6, 2) = .626220703125, (6, 3) = -.4326171875, (6, 4) = .1418304443359375, (6, 5) = -0.861053466796875e-1, (6, 6) = .3131103515625}, datatype = float[8], order = C_order), Array(1..6, {(1) = .0, (2) = .386, (3) = .21, (4) = .63, (5) = 1.0, (6) = 1.0}, datatype = float[8], order = C_order), Array(1..6, {(1) = .25, (2) = -.1043, (3) = .1035, (4) = -0.362e-1, (5) = .0, (6) = .0}, datatype = float[8], order = C_order), Array(1..6, 1..5, {(1, 1) = .0, (1, 2) = .0, (1, 3) = .0, (1, 4) = .0, (1, 5) = .0, (2, 1) = 1.544, (2, 2) = .0, (2, 3) = .0, (2, 4) = .0, (2, 5) = .0, (3, 1) = .9466785280815533, (3, 2) = .25570116989825814, (3, 3) = .0, (3, 4) = .0, (3, 5) = .0, (4, 1) = 3.3148251870684886, (4, 2) = 2.896124015972123, (4, 3) = .9986419139977808, (4, 4) = .0, (4, 5) = .0, (5, 1) = 1.2212245092262748, (5, 2) = 6.019134481287752, (5, 3) = 12.537083329320874, (5, 4) = -.687886036105895, (5, 5) = .0, (6, 1) = 1.2212245092262748, (6, 2) = 6.019134481287752, (6, 3) = 12.537083329320874, (6, 4) = -.687886036105895, (6, 5) = 1.0}, datatype = float[8], order = C_order), Array(1..6, 1..5, {(1, 1) = .0, (1, 2) = .0, (1, 3) = .0, (1, 4) = .0, (1, 5) = .0, (2, 1) = -5.6688, (2, 2) = .0, (2, 3) = .0, (2, 4) = .0, (2, 5) = .0, (3, 1) = -2.4300933568337584, (3, 2) = -.20635991570891224, (3, 3) = .0, (3, 4) = .0, (3, 5) = .0, (4, 1) = -.10735290581452621, (4, 2) = -9.594562251021896, (4, 3) = -20.470286148096154, (4, 4) = .0, (4, 5) = .0, (5, 1) = 7.496443313968615, (5, 2) = -10.246804314641219, (5, 3) = -33.99990352819906, (5, 4) = 11.708908932061595, (5, 5) = .0, (6, 1) = 8.083246795922411, (6, 2) = -7.981132988062785, (6, 3) = -31.52159432874373, (6, 4) = 16.319305431231363, (6, 5) = -6.0588182388340535}, datatype = float[8], order = C_order), Array(1..3, 1..5, {(1, 1) = .0, (1, 2) = .0, (1, 3) = .0, (1, 4) = .0, (1, 5) = .0, (2, 1) = 10.126235083446911, (2, 2) = -7.487995877607633, (2, 3) = -34.800918615557414, (2, 4) = -7.9927717075687275, (2, 5) = 1.0251377232956207, (3, 1) = -.6762803392806898, (3, 2) = 6.087714651678606, (3, 3) = 16.43084320892463, (3, 4) = 24.767225114183653, (3, 5) = -6.5943891257167815}, datatype = float[8], order = C_order)]), ( 9 ) = ([Array(1..1, {(1) = .1}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, 1..1, {(1, 1) = .0}, datatype = float[8], order = C_order), Array(1..1, 1..1, {(1, 1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, 1..1, {(1, 1) = .0}, datatype = float[8], order = C_order), Array(1..1, 1..6, {(1, 1) = .0, (1, 2) = .0, (1, 3) = .0, (1, 4) = .0, (1, 5) = .0, (1, 6) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = 0}, datatype = integer[8]), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..2, {(1) = .0, (2) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = 0}, datatype = integer[8])]), ( 8 ) = ([Array(1..1, {(1) = 3.0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), Array(1..1, {(1) = .0}, datatype = float[8], order = C_order), 0, 0]), ( 11 ) = (Array(1..6, 0..1, {(1, 1) = .0, (2, 0) = .0, (2, 1) = .0, (3, 0) = .0, (3, 1) = .0, (4, 0) = .0, (4, 1) = .0, (5, 0) = .0, (5, 1) = .0, (6, 0) = .0, (6, 1) = .0}, datatype = float[8], order = C_order)), ( 10 ) = ([proc (N, X, Y, YP) option `[Y[1] = y(x)]`; YP[1] := sin(X*Y[1]); 0 end proc, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]), ( 13 ) = (), ( 12 ) = (), ( 15 ) = ("rkf45"), ( 14 ) = ([0, 0]), ( 18 ) = ([]), ( 19 ) = (0), ( 16 ) = ([0, 0, 0, 0, 0, 0, []]), ( 17 ) = ([proc (N, X, Y, YP) option `[Y[1] = y(x)]`; YP[1] := sin(X*Y[1]); 0 end proc, -1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]), ( 22 ) = (0), ( 23 ) = (0), ( 20 ) = ([]), ( 21 ) = (0), ( 27 ) = (""), ( 26 ) = (Array(1..0, {})), ( 25 ) = (Array(1..0, {})), ( 24 ) = (0), ( 28 ) = (0)  ] ))  ] ); _y0 := Array(0..1, {(1) = 0.}); _vmap := array( 1 .. 1, [( 1 ) = (1)  ] ); _x0 := _dtbl[1][5][5]; _n := _dtbl[1][4][1]; _ne := _dtbl[1][4][3]; _nd := _dtbl[1][4][4]; _nv := _dtbl[1][4][16]; if not type(_xout, 'numeric') then if member(_xout, ["start", "left", "right"]) then if _Env_smart_dsolve_numeric = true or _dtbl[1][4][10] = 1 then if _xout = "left" then if type(_dtbl[2], 'table') then return _dtbl[2][5][1] end if elif _xout = "right" then if type(_dtbl[3], 'table') then return _dtbl[3][5][1] end if end if end if; return _dtbl[1][5][5] elif _xout = "method" then return _dtbl[1][15] elif _xout = "storage" then return evalb(_dtbl[1][4][10] = 1) elif _xout = "leftdata" then if not type(_dtbl[2], 'array') then return NULL else return eval(_dtbl[2]) end if elif _xout = "rightdata" then if not type(_dtbl[3], 'array') then return NULL else return eval(_dtbl[3]) end if elif _xout = "enginedata" then return eval(_dtbl[1]) elif _xout = "enginereset" then _dtbl[2] := evaln(_dtbl[2]); _dtbl[3] := evaln(_dtbl[3]); return NULL elif _xout = "initial" then return procname(_y0[0]) elif _xout = "laxtol" then return _dtbl[`if`(member(_dtbl[4], {2, 3}), _dtbl[4], 1)][5][18] elif _xout = "numfun" then return `if`(member(_dtbl[4], {2, 3}), _dtbl[_dtbl[4]][4][18], 0) elif _xout = "parameters" then return [seq(_y0[_n+_i], _i = 1 .. nops(_pars))] elif _xout = "initial_and_parameters" then return procname(_y0[0]), [seq(_y0[_n+_i], _i = 1 .. nops(_pars))] elif _xout = "last" then if _dtbl[4] <> 2 and _dtbl[4] <> 3 or _x0-_dtbl[_dtbl[4]][5][1] = 0. then error "no information is available on last computed point" else _xout := _dtbl[_dtbl[4]][5][1] end if elif _xout = "function" then if _dtbl[1][4][33]-2. = 0 then return eval(_dtbl[1][10], 1) else return eval(_dtbl[1][10][1], 1) end if elif _xout = "map" then return copy(_vmap) elif type(_xin, `=`) and type(rhs(_xin), 'list') and member(lhs(_xin), {"initial", "parameters", "initial_and_parameters"}) then _ini, _par := [], []; if lhs(_xin) = "initial" then _ini := rhs(_xin) elif lhs(_xin) = "parameters" then _par := rhs(_xin) elif select(type, rhs(_xin), `=`) <> [] then _par, _ini := selectremove(type, rhs(_xin), `=`) elif nops(rhs(_xin)) < nops(_pars)+1 then error "insufficient data for specification of initial and parameters" else _par := rhs(_xin)[-nops(_pars) .. -1]; _ini := rhs(_xin)[1 .. -nops(_pars)-1] end if; _xout := lhs(_xout); _i := false; if _par <> [] then _i := `dsolve/numeric/process_parameters`(_n, _pars, _par, _y0) end if; if _ini <> [] then _i := `dsolve/numeric/process_initial`(_n-_ne, _ini, _y0, _pars, _vmap) or _i end if; if _i then `dsolve/numeric/SC/reinitialize`(_dtbl, _y0, _n, procname, _pars); if _Env_smart_dsolve_numeric = true and type(_y0[0], 'numeric') and _dtbl[1][4][10] <> 1 then procname("right") := _y0[0]; procname("left") := _y0[0] end if end if; if _xout = "initial" then return [_y0[0], seq(_y0[_vmap[_i]], _i = 1 .. _n-_ne)] elif _xout = "parameters" then return [seq(_y0[_n+_i], _i = 1 .. nops(_pars))] else return [_y0[0], seq(_y0[_vmap[_i]], _i = 1 .. _n-_ne)], [seq(_y0[_n+_i], _i = 1 .. nops(_pars))] end if elif _xin = "eventstop" then if _nv = 0 then error "this solution has no events" end if; _i := _dtbl[4]; if _i <> 2 and _i <> 3 then return 0 end if; if _dtbl[_i][4][10] = 1 and assigned(_dtbl[5-_i]) and _dtbl[_i][4][9] < 100 and 100 <= _dtbl[5-_i][4][9] then _i := 5-_i; _dtbl[4] := _i; _j := round(_dtbl[_i][4][17]); return round(_dtbl[_i][3][1][_j, 1]) elif 100 <= _dtbl[_i][4][9] then _j := round(_dtbl[_i][4][17]); return round(_dtbl[_i][3][1][_j, 1]) else return 0 end if elif _xin = "eventstatus" then if _nv = 0 then error "this solution has no events" end if; _i := [selectremove(proc (a) options operator, arrow; _dtbl[1][3][1][a, 7] = 1 end proc, {seq(_j, _j = 1 .. round(_dtbl[1][3][1][_nv+1, 1]))})]; return ':-enabled' = _i[1], ':-disabled' = _i[2] elif _xin = "eventclear" then if _nv = 0 then error "this solution has no events" end if; _i := _dtbl[4]; if _i <> 2 and _i <> 3 then error "no events to clear" end if; if _dtbl[_i][4][10] = 1 and assigned(_dtbl[5-_i]) and _dtbl[_i][4][9] < 100 and 100 < _dtbl[5-_i][4][9] then _dtbl[4] := 5-_i; _i := 5-_i end if; if _dtbl[_i][4][9] < 100 then error "no events to clear" elif _nv < _dtbl[_i][4][9]-100 then error "event error condition cannot be cleared" else _j := _dtbl[_i][4][9]-100; if irem(round(_dtbl[_i][3][1][_j, 4]), 2) = 1 then error "retriggerable events cannot be cleared" end if; _j := round(_dtbl[_i][3][1][_j, 1]); for _k to _nv do if _dtbl[_i][3][1][_k, 1] = _j then if _dtbl[_i][3][1][_k, 2] = 3 then error "range events cannot be cleared" end if; _dtbl[_i][3][1][_k, 8] := _dtbl[_i][3][1][_nv+1, 8] end if end do; _dtbl[_i][4][17] := 0; _dtbl[_i][4][9] := 0; if _dtbl[1][4][10] = 1 then if _i = 2 then try procname(procname("left")) catch:  end try else try procname(procname("right")) catch:  end try end if end if end if; return  elif type(_xin, `=`) and member(lhs(_xin), {"eventdisable", "eventenable"}) then if _nv = 0 then error "this solution has no events" end if; if type(rhs(_xin), {('list')('posint'), ('set')('posint')}) then _i := {op(rhs(_xin))} elif type(rhs(_xin), 'posint') then _i := {rhs(_xin)} else error "event identifiers must be integers in the range 1..%1", round(_dtbl[1][3][1][_nv+1, 1]) end if; if select(proc (a) options operator, arrow; _nv < a end proc, _i) <> {} then error "event identifiers must be integers in the range 1..%1", round(_dtbl[1][3][1][_nv+1, 1]) end if; _k := {}; for _j to _nv do if member(round(_dtbl[1][3][1][_j, 1]), _i) then _k := `union`(_k, {_j}) end if end do; _i := _k; if lhs(_xin) = "eventdisable" then _dtbl[4] := 0; _j := [evalb(assigned(_dtbl[2]) and member(_dtbl[2][4][17], _i)), evalb(assigned(_dtbl[3]) and member(_dtbl[3][4][17], _i))]; for _k in _i do _dtbl[1][3][1][_k, 7] := 0; if assigned(_dtbl[2]) then _dtbl[2][3][1][_k, 7] := 0 end if; if assigned(_dtbl[3]) then _dtbl[3][3][1][_k, 7] := 0 end if end do; if _j[1] then for _k to _nv+1 do if _k <= _nv and not type(_dtbl[2][3][4][_k, 1], 'undefined') then userinfo(3, {'events', 'eventreset'}, `reinit #2, event code `, _k, ` to defined init `, _dtbl[2][3][4][_k, 1]); _dtbl[2][3][1][_k, 8] := _dtbl[2][3][4][_k, 1] elif _dtbl[2][3][1][_k, 2] = 0 and irem(iquo(round(_dtbl[2][3][1][_k, 4]), 32), 2) = 1 then userinfo(3, {'events', 'eventreset'}, `reinit #2, event code `, _k, ` to rate hysteresis init `, _dtbl[2][5][24]); _dtbl[2][3][1][_k, 8] := _dtbl[2][5][24] elif _dtbl[2][3][1][_k, 2] = 0 and irem(iquo(round(_dtbl[2][3][1][_k, 4]), 2), 2) = 0 then userinfo(3, {'events', 'eventreset'}, `reinit #2, event code `, _k, ` to initial init `, _x0); _dtbl[2][3][1][_k, 8] := _x0 else userinfo(3, {'events', 'eventreset'}, `reinit #2, event code `, _k, ` to fireinitial init `, _x0-1); _dtbl[2][3][1][_k, 8] := _x0-1 end if end do; _dtbl[2][4][17] := 0; _dtbl[2][4][9] := 0; if _dtbl[1][4][10] = 1 then procname(procname("left")) end if end if; if _j[2] then for _k to _nv+1 do if _k <= _nv and not type(_dtbl[3][3][4][_k, 2], 'undefined') then userinfo(3, {'events', 'eventreset'}, `reinit #3, event code `, _k, ` to defined init `, _dtbl[3][3][4][_k, 2]); _dtbl[3][3][1][_k, 8] := _dtbl[3][3][4][_k, 2] elif _dtbl[3][3][1][_k, 2] = 0 and irem(iquo(round(_dtbl[3][3][1][_k, 4]), 32), 2) = 1 then userinfo(3, {'events', 'eventreset'}, `reinit #3, event code `, _k, ` to rate hysteresis init `, _dtbl[3][5][24]); _dtbl[3][3][1][_k, 8] := _dtbl[3][5][24] elif _dtbl[3][3][1][_k, 2] = 0 and irem(iquo(round(_dtbl[3][3][1][_k, 4]), 2), 2) = 0 then userinfo(3, {'events', 'eventreset'}, `reinit #3, event code `, _k, ` to initial init `, _x0); _dtbl[3][3][1][_k, 8] := _x0 else userinfo(3, {'events', 'eventreset'}, `reinit #3, event code `, _k, ` to fireinitial init `, _x0+1); _dtbl[3][3][1][_k, 8] := _x0+1 end if end do; _dtbl[3][4][17] := 0; _dtbl[3][4][9] := 0; if _dtbl[1][4][10] = 1 then procname(procname("right")) end if end if else for _k in _i do _dtbl[1][3][1][_k, 7] := 1 end do; _dtbl[2] := evaln(_dtbl[2]); _dtbl[3] := evaln(_dtbl[3]); _dtbl[4] := 0; if _dtbl[1][4][10] = 1 then if _x0 <= procname("right") then try procname(procname("right")) catch:  end try end if; if procname("left") <= _x0 then try procname(procname("left")) catch:  end try end if end if end if; return  elif type(_xin, `=`) and lhs(_xin) = "eventfired" then if not type(rhs(_xin), 'list') then error "'eventfired' must be specified as a list" end if; if _nv = 0 then error "this solution has no events" end if; if _dtbl[4] <> 2 and _dtbl[4] <> 3 then error "'direction' must be set prior to calling/setting 'eventfired'" end if; _i := _dtbl[4]; _val := NULL; if not assigned(_EnvEventRetriggerWarned) then _EnvEventRetriggerWarned := false end if; for _k in rhs(_xin) do if type(_k, 'integer') then _src := _k elif type(_k, 'integer' = 'anything') and type(evalf(rhs(_k)), 'numeric') then _k := lhs(_k) = evalf[max(Digits, 18)](rhs(_k)); _src := lhs(_k) else error "'eventfired' entry is not valid: %1", _k end if; if _src < 1 or round(_dtbl[1][3][1][_nv+1, 1]) < _src then error "event identifiers must be integers in the range 1..%1", round(_dtbl[1][3][1][_nv+1, 1]) end if; _src := {seq(`if`(_dtbl[1][3][1][_j, 1]-_src = 0., _j, NULL), _j = 1 .. _nv)}; if nops(_src) <> 1 then error "'eventfired' can only be set/queried for root-finding events and time/interval events" end if; _src := _src[1]; if _dtbl[1][3][1][_src, 2] <> 0. and _dtbl[1][3][1][_src, 2]-2. <> 0. then error "'eventfired' can only be set/queried for root-finding events and time/interval events" elif irem(round(_dtbl[1][3][1][_src, 4]), 2) = 1 then if _EnvEventRetriggerWarned = false then WARNING(`'eventfired' has no effect on events that retrigger`) end if; _EnvEventRetriggerWarned := true end if; if _dtbl[_i][3][1][_src, 2] = 0 and irem(iquo(round(_dtbl[_i][3][1][_src, 4]), 32), 2) = 1 then _val := _val, undefined elif type(_dtbl[_i][3][4][_src, _i-1], 'undefined') or _i = 2 and _dtbl[2][3][1][_src, 8] < _dtbl[2][3][4][_src, 1] or _i = 3 and _dtbl[3][3][4][_src, 2] < _dtbl[3][3][1][_src, 8] then _val := _val, _dtbl[_i][3][1][_src, 8] else _val := _val, _dtbl[_i][3][4][_src, _i-1] end if; if type(_k, `=`) then if _dtbl[_i][3][1][_src, 2] = 0 and irem(iquo(round(_dtbl[_i][3][1][_src, 4]), 32), 2) = 1 then error "cannot set event code for a rate hysteresis event" end if; userinfo(3, {'events', 'eventreset'}, `manual set event code `, _src, ` to value `, rhs(_k)); _dtbl[_i][3][1][_src, 8] := rhs(_k); _dtbl[_i][3][4][_src, _i-1] := rhs(_k) end if end do; return [_val] elif type(_xin, `=`) and lhs(_xin) = "direction" then if not member(rhs(_xin), {-1, 1, ':-left', ':-right'}) then error "'direction' must be specified as either '1' or 'right' (positive) or '-1' or 'left' (negative)" end if; _src := `if`(_dtbl[4] = 2, -1, `if`(_dtbl[4] = 3, 1, undefined)); _i := `if`(member(rhs(_xin), {1, ':-right'}), 3, 2); _dtbl[4] := _i; _dtbl[_i] := `dsolve/numeric/SC/IVPdcopy`(_dtbl[1], `if`(assigned(_dtbl[_i]), _dtbl[_i], NULL)); if 0 < _nv then for _j to _nv+1 do if _j <= _nv and not type(_dtbl[_i][3][4][_j, _i-1], 'undefined') then userinfo(3, {'events', 'eventreset'}, `reinit #4, event code `, _j, ` to defined init `, _dtbl[_i][3][4][_j, _i-1]); _dtbl[_i][3][1][_j, 8] := _dtbl[_i][3][4][_j, _i-1] elif _dtbl[_i][3][1][_j, 2] = 0 and irem(iquo(round(_dtbl[_i][3][1][_j, 4]), 32), 2) = 1 then userinfo(3, {'events', 'eventreset'}, `reinit #4, event code `, _j, ` to rate hysteresis init `, _dtbl[_i][5][24]); _dtbl[_i][3][1][_j, 8] := _dtbl[_i][5][24] elif _dtbl[_i][3][1][_j, 2] = 0 and irem(iquo(round(_dtbl[_i][3][1][_j, 4]), 2), 2) = 0 then userinfo(3, {'events', 'eventreset'}, `reinit #4, event code `, _j, ` to initial init `, _x0); _dtbl[_i][3][1][_j, 8] := _x0 else userinfo(3, {'events', 'eventreset'}, `reinit #4, event code `, _j, ` to fireinitial init `, _x0-2*_i+5.0); _dtbl[_i][3][1][_j, 8] := _x0-2*_i+5.0 end if end do end if; return _src elif _xin = "eventcount" then if _dtbl[1][3][1] = 0 or _dtbl[4] <> 2 and _dtbl[4] <> 3 then return 0 else return round(_dtbl[_dtbl[4]][3][1][_nv+1, 12]) end if elif type(_xin, `=`) and lhs(_xin) = "setdatacallback" then if not type(rhs(_xin), 'nonegint') then error "data callback must be a nonnegative integer (address)" end if; _dtbl[1][28] := rhs(_xin) else return "procname" end if end if; if _xout = _x0 then return [_x0, seq(evalf(_dtbl[1][6][_vmap[_i]]), _i = 1 .. _n-_ne)] end if; _i := `if`(_x0 <= _xout, 3, 2); if _xin = "last" and 0 < _dtbl[_i][4][9] and _dtbl[_i][4][9] < 100 then _dat := eval(_dtbl[_i], 2); _j := _dat[4][20]; return [_dat[11][_j, 0], seq(_dat[11][_j, _vmap[_i]], _i = 1 .. _n-_ne-_nd), seq(_dat[8][1][_vmap[_i]], _i = _n-_ne-_nd+1 .. _n-_ne)] end if; if not type(_dtbl[_i], 'array') then _dtbl[_i] := `dsolve/numeric/SC/IVPdcopy`(_dtbl[1], `if`(assigned(_dtbl[_i]), _dtbl[_i], NULL)); if 0 < _nv then for _j to _nv+1 do if _j <= _nv and not type(_dtbl[_i][3][4][_j, _i-1], 'undefined') then userinfo(3, {'events', 'eventreset'}, `reinit #5, event code `, _j, ` to defined init `, _dtbl[_i][3][4][_j, _i-1]); _dtbl[_i][3][1][_j, 8] := _dtbl[_i][3][4][_j, _i-1] elif _dtbl[_i][3][1][_j, 2] = 0 and irem(iquo(round(_dtbl[_i][3][1][_j, 4]), 32), 2) = 1 then userinfo(3, {'events', 'eventreset'}, `reinit #5, event code `, _j, ` to rate hysteresis init `, _dtbl[_i][5][24]); _dtbl[_i][3][1][_j, 8] := _dtbl[_i][5][24] elif _dtbl[_i][3][1][_j, 2] = 0 and irem(iquo(round(_dtbl[_i][3][1][_j, 4]), 2), 2) = 0 then userinfo(3, {'events', 'eventreset'}, `reinit #5, event code `, _j, ` to initial init `, _x0); _dtbl[_i][3][1][_j, 8] := _x0 else userinfo(3, {'events', 'eventreset'}, `reinit #5, event code `, _j, ` to fireinitial init `, _x0-2*_i+5.0); _dtbl[_i][3][1][_j, 8] := _x0-2*_i+5.0 end if end do end if end if; if _xin <> "last" then if 0 < 0 then if `dsolve/numeric/checkglobals`(op(_dtbl[1][14]), _pars, _n, _y0) then `dsolve/numeric/SC/reinitialize`(_dtbl, _y0, _n, procname, _pars, _i) end if end if; if _dtbl[1][4][7] = 0 then error "parameters must be initialized before solution can be computed" end if end if; _dat := eval(_dtbl[_i], 2); _dtbl[4] := _i; try _src := `dsolve/numeric/SC/IVPrun`(_dat, _xout) catch: userinfo(2, `dsolve/debug`, print(`Exception in solnproc:`, [lastexception][2 .. -1])); error  end try; if _dat[17] <> _dtbl[1][17] then _dtbl[1][17] := _dat[17]; _dtbl[1][10] := _dat[10] end if; if _src = 0 and 100 < _dat[4][9] then _val := _dat[3][1][_nv+1, 8] else _val := _dat[11][_dat[4][20], 0] end if; if _src <> 0 or _dat[4][9] <= 0 then _dtbl[1][5][1] := _xout else _dtbl[1][5][1] := _val end if; if _i = 3 and _val < _xout then Rounding := -infinity; if _dat[4][9] = 1 then error "cannot evaluate the solution further right of %1, probably a singularity", evalf[8](_val) elif _dat[4][9] = 2 then error "cannot evaluate the solution further right of %1, maxfun limit exceeded (see <a href='http://www.maplesoft.com/support/help/search.aspx?term=dsolve,maxfun' target='_new'>?dsolve,maxfun</a> for details)", evalf[8](_val) elif _dat[4][9] = 3 then if _dat[4][25] = 3 then error "cannot evaluate the solution past the initial point, problem may be initially singular or improperly set up" else error "cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up" end if elif _dat[4][9] = 4 then error "cannot evaluate the solution further right of %1, accuracy goal cannot be achieved with specified 'minstep'", evalf[8](_val) elif _dat[4][9] = 5 then error "cannot evaluate the solution further right of %1, too many step failures, tolerances may be too loose for problem", evalf[8](_val) elif _dat[4][9] = 6 then error "cannot evaluate the solution further right of %1, cannot downgrade delay storage for problems with delay derivative order > 1, try increasing delaypts", evalf[8](_val) elif _dat[4][9] = 10 then error "cannot evaluate the solution further right of %1, interrupt requested", evalf[8](_val) elif 100 < _dat[4][9] then if _dat[4][9]-100 = _nv+1 then error "constraint projection failure on event at t=%1", evalf[8](_val) elif _dat[4][9]-100 = _nv+2 then error "index-1 and derivative evaluation failure on event at t=%1", evalf[8](_val) elif _dat[4][9]-100 = _nv+3 then error "maximum number of event iterations reached (%1) at t=%2", round(_dat[3][1][_nv+1, 3]), evalf[8](_val) else if _Env_dsolve_nowarnstop <> true then `dsolve/numeric/warning`(StringTools:-FormatMessage("cannot evaluate the solution further right of %1, event #%2 triggered a halt", evalf[8](_val), round(_dat[3][1][_dat[4][9]-100, 1]))) end if; Rounding := 'nearest'; _xout := _val end if else error "cannot evaluate the solution further right of %1", evalf[8](_val) end if elif _i = 2 and _xout < _val then Rounding := infinity; if _dat[4][9] = 1 then error "cannot evaluate the solution further left of %1, probably a singularity", evalf[8](_val) elif _dat[4][9] = 2 then error "cannot evaluate the solution further left of %1, maxfun limit exceeded (see <a href='http://www.maplesoft.com/support/help/search.aspx?term=dsolve,maxfun' target='_new'>?dsolve,maxfun</a> for details)", evalf[8](_val) elif _dat[4][9] = 3 then if _dat[4][25] = 3 then error "cannot evaluate the solution past the initial point, problem may be initially singular or improperly set up" else error "cannot evaluate the solution past the initial point, problem may be complex, initially singular or improperly set up" end if elif _dat[4][9] = 4 then error "cannot evaluate the solution further left of %1, accuracy goal cannot be achieved with specified 'minstep'", evalf[8](_val) elif _dat[4][9] = 5 then error "cannot evaluate the solution further left of %1, too many step failures, tolerances may be too loose for problem", evalf[8](_val) elif _dat[4][9] = 6 then error "cannot evaluate the solution further left of %1, cannot downgrade delay storage for problems with delay derivative order > 1, try increasing delaypts", evalf[8](_val) elif _dat[4][9] = 10 then error "cannot evaluate the solution further right of %1, interrupt requested", evalf[8](_val) elif 100 < _dat[4][9] then if _dat[4][9]-100 = _nv+1 then error "constraint projection failure on event at t=%1", evalf[8](_val) elif _dat[4][9]-100 = _nv+2 then error "index-1 and derivative evaluation failure on event at t=%1", evalf[8](_val) elif _dat[4][9]-100 = _nv+3 then error "maximum number of event iterations reached (%1) at t=%2", round(_dat[3][1][_nv+1, 3]), evalf[8](_val) else if _Env_dsolve_nowarnstop <> true then `dsolve/numeric/warning`(StringTools:-FormatMessage("cannot evaluate the solution further left of %1, event #%2 triggered a halt", evalf[8](_val), round(_dat[3][1][_dat[4][9]-100, 1]))) end if; Rounding := 'nearest'; _xout := _val end if else error "cannot evaluate the solution further left of %1", evalf[8](_val) end if end if; if _EnvInFsolve = true then _dig := _dat[4][26]; if type(_EnvDSNumericSaveDigits, 'posint') then _dat[4][26] := _EnvDSNumericSaveDigits else _dat[4][26] := Digits end if; _Env_dsolve_SC_native := true; if _dat[4][25] = 1 then _i := 1; _dat[4][25] := 2 else _i := _dat[4][25] end if; _val := `dsolve/numeric/SC/IVPval`(_dat, _xout, _src); _dat[4][25] := _i; _dat[4][26] := _dig; [_xout, seq(_val[_vmap[_i]], _i = 1 .. _n-_ne)] else Digits := _dat[4][26]; _val := `dsolve/numeric/SC/IVPval`(eval(_dat, 2), _xout, _src); [_xout, seq(_val[_vmap[_i]], _i = 1 .. _n-_ne)] end if end proc, (2) = Array(0..0, {}), (3) = [x, y(x)], (4) = []}); _vars := _dat[3]; _pars := map(lhs, _dat[4]); _n := nops(_vars)-1; _solnproc := _dat[1]; if not type(_xout, 'numeric') then if member(x_rkf45, ["start", 'start', "method", 'method', "left", 'left', "right", 'right', "leftdata", "rightdata", "enginedata", "eventstop", 'eventstop', "eventclear", 'eventclear', "eventstatus", 'eventstatus', "eventcount", 'eventcount', "laxtol", 'laxtol', "numfun", 'numfun', NULL]) then _res := _solnproc(convert(x_rkf45, 'string')); if 1 < nops([_res]) then return _res elif type(_res, 'array') then return eval(_res, 1) elif _res <> "procname" then return _res end if elif member(x_rkf45, ["last", 'last', "initial", 'initial', "parameters", 'parameters', "initial_and_parameters", 'initial_and_parameters', NULL]) then _xout := convert(x_rkf45, 'string'); _res := _solnproc(_xout); if _xout = "parameters" then return [seq(_pars[_i] = _res[_i], _i = 1 .. nops(_pars))] elif _xout = "initial_and_parameters" then return [seq(_vars[_i+1] = [_res][1][_i+1], _i = 0 .. _n), seq(_pars[_i] = [_res][2][_i], _i = 1 .. nops(_pars))] else return [seq(_vars[_i+1] = _res[_i+1], _i = 0 .. _n)] end if elif type(_xout, `=`) and member(lhs(_xout), ["initial", 'initial', "parameters", 'parameters', "initial_and_parameters", 'initial_and_parameters', NULL]) then _xout := convert(lhs(x_rkf45), 'string') = rhs(x_rkf45); if type(rhs(_xout), 'list') then _res := _solnproc(_xout) else error "initial and/or parameter values must be specified in a list" end if; if lhs(_xout) = "initial" then return [seq(_vars[_i+1] = _res[_i+1], _i = 0 .. _n)] elif lhs(_xout) = "parameters" then return [seq(_pars[_i] = _res[_i], _i = 1 .. nops(_pars))] else return [seq(_vars[_i+1] = [_res][1][_i+1], _i = 0 .. _n), seq(_pars[_i] = [_res][2][_i], _i = 1 .. nops(_pars))] end if elif type(_xout, `=`) and member(lhs(_xout), ["eventdisable", 'eventdisable', "eventenable", 'eventenable', "eventfired", 'eventfired', "direction", 'direction', NULL]) then return _solnproc(convert(lhs(x_rkf45), 'string') = rhs(x_rkf45)) elif _xout = "solnprocedure" then return eval(_solnproc) elif _xout = "sysvars" then return _vars end if; if procname <> unknown then return ('procname')(x_rkf45) else _ndsol := 1; _ndsol := _ndsol; _ndsol := pointto(_dat[2][0]); return ('_ndsol')(x_rkf45) end if end if; try _res := _solnproc(_xout); [seq(_vars[_i+1] = _res[_i+1], _i = 0 .. _n)] catch: error  end try end proc

    (6)

    [soln(1), soln(1.5), soln(2), soln(2.5), soln(3), soln(3.5), soln(4), soln(4.5), soln(5)]

    [[x = 1., y(x) = HFloat(3.5280317971877286)], [x = 1.5, y(x) = HFloat(3.1226400064202693)], [x = 2., y(x) = HFloat(2.653970420106217)], [x = 2.5, y(x) = HFloat(2.323175669304077)], [x = 3., y(x) = HFloat(2.3019187052877816)], [x = 3.5, y(x) = HFloat(2.6587033583656714)], [x = 4., y(x) = HFloat(2.497876146260152)], [x = 4.5, y(x) = HFloat(2.220305976552359)], [x = 5., y(x) = HFloat(1.9758297601444128)]]

    (7)

    p1 := odeplot(soln, [x, y(x)], x = 0 .. 5, color = magenta, thickness = 2, scaling = constrained, view = [0 .. 5, 0 .. 5])

     

    p2 := dfieldplot(ODE2, [y(x)], x = 0 .. 5, y = 0 .. 5, color = blue, scaling = constrained)

    display(p1, p2)

     

    DEplot(ODE2, y(x), x = 0 .. 5, y = 0 .. 5, [[y(0) = 3]], linecolor = red, color = blue, scaling = constrained, axes = boxed)

     

    Construct approximate solutions for x from 0 to 5 to the initial problem 2 using Euler's method with the three different step sizes Δx=0.5, 0.25, 0.125

    f := proc (x, y) options operator, arrow; sin(x*y) end proc

    proc (x, y) options operator, arrow; sin(y*x) end proc

    (8)

    Eulermethod := proc (f, x_start, y_start, dx, n_total) local x, y, Y, i, k; x[1] := x_start; y[1] := y_start; for i to n_total do y[i+1] := y[i]+f(x[i], y[i])*dx; x[i+1] := x[1]+i*dx end do; Y := [seq([x[k], y[k]], k = 1 .. n_total)]; return Y end proc

    proc (f, x_start, y_start, dx, n_total) local x, y, Y, i, k; x[1] := x_start; y[1] := y_start; for i to n_total do y[i+1] := y[i]+f(x[i], y[i])*dx; x[i+1] := x[1]+i*dx end do; Y := [seq([x[k], y[k]], k = 1 .. n_total)]; return Y end proc

    (9)

    NULL

    NULL

    NULL

    NULL

    A1 := Eulermethod(f, 0, 3, .5, 10)

    [[0, 3], [.5, 3.], [1.0, 3.498747493], [1.5, 3.323942476], [2.0, 2.842530099], [2.5, 2.560983065], [3.0, 2.620477947], [3.5, 3.120464063], [4.0, 2.621830593], [4.5, 2.185032319]]

    (10)

    A2 := Eulermethod(f, 0, 3, .25, 20)

    [[0, 3], [.25, 3.], [.50, 3.170409690], [.75, 3.420383740], [1.00, 3.556616077], [1.25, 3.455813236], [1.50, 3.224836021], [1.75, 2.976782400], [2.00, 2.757025820], [2.25, 2.583147563], [2.50, 2.469680146], [2.75, 2.442487816], [3.00, 2.547535655], [3.25, 2.791971512], [3.50, 2.877900373], [3.75, 2.727027361], [4.00, 2.547414295], [4.25, 2.374301829], [4.50, 2.219839448], [4.75, 2.086091178]]

    (11)

    A3 := Eulermethod(f, 0, 3, .125, 40)

    [[0, 3], [.125, 3.], [.250, 3.045784066], [.375, 3.132030172], [.500, 3.247342837], [.625, 3.372168142], [.750, 3.479586272], [.875, 3.542983060], [1.000, 3.548166882], [1.125, 3.498733738], [1.250, 3.409546073], [1.375, 3.297015011], [1.500, 3.174012084], [1.625, 3.049159854], [1.750, 2.927817142], [1.875, 2.813241461], [2.000, 2.707496816], [2.125, 2.612101612], [2.250, 2.528513147], [2.375, 2.458549923], [2.500, 2.404840953], [2.625, 2.371369082], [2.750, 2.364080535], [2.875, 2.391119623], [3.000, 2.460798019], [3.125, 2.572154041], [3.250, 2.695044010], [3.375, 2.772263417], [3.500, 2.780805371], [3.625, 2.742906337], [3.750, 2.680985435], [3.875, 2.607451728], [4.000, 2.528940353], [4.125, 2.449278434], [4.250, 2.370825619], [4.375, 2.295054886], [4.500, 2.222824117], [4.625, 2.154537647], [4.750, 2.090275081], [4.875, 2.029905439]]

    (12)

    NULL

    p3 := pointplot(A1, color = green, scaling = constrained, symbol = circle)

    p4 := pointplot(A2, color = black, scaling = constrained, symbol = asterisk)

    p5 := pointplot(A3, color = red, scaling = constrained, symbol = diamond)

    NULL

    display([p1, p3, p4, p5])

     

    NULL

    In this plot, the differences between the lines visually represent how using different step sizes affects the overall solution accuracy. The red points are closest to what a more accurate numerical solution would look like, while the green points are more of a rough approximation.

     

     

    Problem 3 (IMPROVED EULER METHOD

    ``

     

     

     

    ImprovedEulermethod := proc (f, x_start, y_start, dx, n_total) local x, y, Y, i, k, k1, k2; x[1] := x_start; y[1] := y_start; for i to n_total do k1 := f(x[i], y[i]); k2 := f(x[i]+dx, y[i]+k1*dx); y[i+1] := y[i]+(1/2)*dx*(k1+k2); x[i+1] := x[1]+i*dx end do; Y := [seq([x[k], y[k]], k = 1 .. n_total+1)]; return Y end proc

    proc (f, x_start, y_start, dx, n_total) local x, y, Y, i, k, k1, k2; x[1] := x_start; y[1] := y_start; for i to n_total do k1 := f(x[i], y[i]); k2 := f(x[i]+dx, y[i]+k1*dx); y[i+1] := y[i]+(1/2)*dx*(k1+k2); x[i+1] := x[1]+i*dx end do; Y := [seq([x[k], y[k]], k = 1 .. n_total+1)]; return Y end proc

    (13)

    A := ImprovedEulermethod(f, 0, 3, .5, 10); B := ImprovedEulermethod(f, 0, 3, .25, 20); C := ImprovedEulermethod(f, 0, 3, .125, 40)

    [[0, 3], [.125, 3.022892033], [.250, 3.089335383], [.375, 3.190999573], [.500, 3.311460714], [.625, 3.426126738], [.750, 3.508312296], [.875, 3.539992283], [1.000, 3.518184043], [1.125, 3.451931748], [1.250, 3.354946855], [1.375, 3.240089444], [1.500, 3.117181611], [1.625, 2.992925708], [1.750, 2.871597591], [1.875, 2.755823574], [2.000, 2.647215450], [2.125, 2.546845751], [2.250, 2.455612702], [2.375, 2.374560360], [2.500, 2.305227222], [2.625, 2.250113264], [2.750, 2.213376654], [2.875, 2.201814459], [3.000, 2.225589190], [3.125, 2.295322044], [3.250, 2.406184220], [3.375, 2.516909932], [3.500, 2.583378006], [3.625, 2.599915321], [3.750, 2.579967129], [3.875, 2.537160528], [4.000, 2.481052245], [4.125, 2.417781798], [4.250, 2.351265142], [4.375, 2.284028571], [4.500, 2.217702881], [4.625, 2.153313287], [4.750, 2.091461577], [4.875, 2.032452273], [5.000, 1.976386380]]

    (14)

    NULL

    plot2 := pointplot(A, color = green, scaling = constrained, symbol = circle)

    plot3 := pointplot(B, color = black, scaling = constrained, symbol = asterisk)

    plot4 := pointplot(C, color = red, scaling = constrained, symbol = diamond)

    NULL

    display([p1, plot2, plot3, plot4])

     

    The Improved Euler method, by averaging slopes, provides a significant improvement over the basic Euler method, particularly when the step size is relatively large.


    Download Diff_equations.mw

    Hello,

    Below I am attaching a Maple worksheet on rolling a circle on a flat curve and generating a cycloidal curve.

    Regards!

    Cycloidal_curve.mw



     

    This is a task from one forum:  “Let's mark an arbitrary point on the circle. Let's draw a segment from this point, perpendicular to the diameter, and draw a circle, the center of which is at this point, and the radius is equal to this segment. Let's mark the intersection point of the segment connecting the intersection points of the circles with the perpendicular segment. Prove that the locus of all such points is an ellipse.”
    I wanted to get a picture of a numerically animated "proof" using Maple tools.

    МАTH_HЕLP_PLANET.mw
     And in fact, it turned out that AB=2AC, or AC=BC.

    In this post, I would like to share some exercises that I recently taught to an undergraduate student using Maple. These exercises aimed to deepen their understanding of mathematical concepts through computational exploration and visualization. With its powerful symbolic computation capabilities, Maple proved to be an excellent tool for this purpose. Below, I present a few of the exercises and the insights they provided. Interestingly, the student found Maple to be more user-friendly and efficient compared to the software he usually uses for his studies. Below, I present a few of the exercises and the insights they provided.

    One of the first topics we tackled was the Fourier series. We used Maple to illustrate how the Fourier series approximates a given function as more terms are added. We explored this through both static plots and interactive animations.

    To help the student understand the behavior of different types of functions, we defined piecewise functions using Maple's piecewise command. This allowed us to model functions that behave differently over various intervals, such as the following cubic function exercise

    Maple's Explore command was an effective tool for creating an interactive learning environment. We used it to create sliders that allowed the student to vary parameters, such as the number of terms in a Fourier series, and see the immediate impact on the plot.

    restart; with(plots)

    " F(x):={[[-1,-1<x<0],[1,0<x<1]];  "

    proc (x) options operator, arrow, function_assign; piecewise(-1 < x and x < 0, -1, 0 < x and x < 1, 1) end proc

    (1)

    p1 := plot(piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), x = -3 .. 3, color = blue)

     

    L := 2; a__0 := (int(F(x), x = -(1/2)*L .. (1/2)*L))/L

    0

    (2)

    a__n := proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (3)

    b__n := proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (4)

    " #` Fourier series function`  `F__fourier`(x,N):=`a__0`+(&sum;)(`a__n`(n)&lowast;cos(2 * n * Pi * x / L) +`b__n`(n)&lowast;sin(2* n * Pi * x / L));"

    proc (x, N) options operator, arrow, function_assign; a__0+sum(a__n(n)*cos(2*n*Pi*x/L)+b__n(n)*sin(2*n*Pi*x/L), n = 1 .. N) end proc

    (5)

    p2 := plot([F__fourier(x, 40)], x = -3 .. 3, numpoints = 200, color = [purple])

    display([p1, p2])

     

    Explore(plot([piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), F__fourier(x, N)], x = -3 .. 3, color = [blue, purple], numpoints = 200), N = 1 .. 40, title = "Fourier Series Approximation with N Terms")

    restart; with(plots)

    " #` Define the piecewise function`  F(x):={[[0,-1<x<0],[x^(2),0<x<1]];  "

    proc (x) options operator, arrow, function_assign; piecewise(-1 < x and x < 0, 0, 0 < x and x < 1, x^2) end proc

    (6)

    p3 := plot(piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), x = -3 .. 3, color = blue)

     

    L := 2; a__0 := (int(F(x), x = -(1/2)*L .. (1/2)*L))/L

    1/6

    (7)

    a__n := proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (8)

    b__n := proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (9)

    " #` Fourier series function`  `F__fourier`(x,N):=`a__0`+(&sum;)(`a__n`(n)&lowast;cos(2 * n * Pi * x / L) +`b__n`(n)&lowast;sin(2* n * Pi * x / L));"

    proc (x, N) options operator, arrow, function_assign; a__0+sum(a__n(n)*cos(2*n*Pi*x/L)+b__n(n)*sin(2*n*Pi*x/L), n = 1 .. N) end proc

    (10)

    p4 := plot([F__fourier(x, 40)], x = -3 .. 3, numpoints = 200, color = [purple])

    display([p3, p4])

     

    Explore(plot([piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), F__fourier(x, N)], x = -3 .. 3, color = [blue, purple], numpoints = 200), N = 1 .. 40, title = "Fourier Series Approximation with N Terms")

    restart; with(plots)

    " #` Define the piecewise function`  F(x):={[[x+2,-2<x<0],[2-2 x,0<x<2]]; "

    proc (x) options operator, arrow, function_assign; piecewise(-2 < x and x < 0, x+2, 0 < x and x < 2, 2-2*x) end proc

    (11)

    p5 := plot(piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), x = -3 .. 3, color = blue)

     

    L := 2; a__0 := (int(F(x), x = -(1/2)*L .. (1/2)*L))/L

    5/4

    (12)

    a__n := proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (13)

    b__n := proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (14)

    " #` Fourier series function`  `F__fourier`(x,N):=`a__0`+(&sum;)(`a__n`(n)&lowast;cos(2 * n * Pi * x / L) +`b__n`(n)&lowast;sin(2* n * Pi * x / L));"

    proc (x, N) options operator, arrow, function_assign; a__0+sum(a__n(n)*cos(2*n*Pi*x/L)+b__n(n)*sin(2*n*Pi*x/L), n = 1 .. N) end proc

    (15)

    p6 := plot([F__fourier(x, 40)], x = -3 .. 3, numpoints = 200, color = [purple])

    display([p5, p6])

     

    Explore(plot([piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), F__fourier(x, N)], x = -3 .. 3, color = [blue, purple], numpoints = 200), N = 1 .. 40, title = "Fourier Series Approximation with N Terms")

    restart; with(plots)

    F := proc (x) options operator, arrow; piecewise(-1 < x and x < 1, x-x^3, 0) end proc

    proc (x) options operator, arrow; piecewise(-1 < x and x < 1, x-x^3, 0) end proc

    (16)

    p7 := plot(piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), x = -3 .. 3, color = blue)

     

    L := 2; a__0 := (int(F(x), x = -(1/2)*L .. (1/2)*L))/L

    0

    (17)

    a__n := proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*cos(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (18)

    b__n := proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    proc (n) options operator, arrow; 2*(int(F(x)*sin(2*n*Pi*x/L), x = -(1/2)*L .. (1/2)*L))/L end proc

    (19)

    b__n(n)

    -4*(n^2*Pi^2*sin(n*Pi)+3*cos(n*Pi)*Pi*n-3*sin(n*Pi))/(n^4*Pi^4)

    (20)

    " #` Fourier series function`  `F__fourier`(x,N):=`a__0`+(&sum;)(`a__n`(n)&lowast;cos(2 * n * Pi * x / L) +`b__n`(n)&lowast;sin(2* n * Pi * x / L));      #` Plot the Fourier series approximation`  p8:=plot([`F__fourier`(x,40)],x = -3.. 3 ,numpoints=200, color=[red]) :"

    proc (x, N) options operator, arrow, function_assign; a__0+sum(a__n(n)*cos(2*n*Pi*x/L)+b__n(n)*sin(2*n*Pi*x/L), n = 1 .. N) end proc

    (21)

    display([p7, p8])

     

    Explore(plot([piecewise(-3 < x and x < -1, F(x+2), -1 < x and x < 1, F(x), 1 < x and x < 3, F(x-2)), F__fourier(x, N)], x = -3 .. 3, color = [blue, purple], numpoints = 200), N = 1 .. 40, title = "Fourier Series Approximation with N Terms")

    NULL

    Download Fourier_Series.mw

    Source codes (seen in the pdf file) for the paper "Maximal Gap Among Integers Having a Common Divisor with an Odd Semi-prime".

    MaxGapTheorem2.pdf

    The flag of Germany on the strip of the German mathematician August Ferdinand Möbius. Basically, it's just one way to represent flags of a certain type. It seemed that the flag looked good on the Mobius strip.
    FLAG.mw

    Hello!

    I present a simple work-up of rolling a plane curve along a fixed plane curve in 2d space. Maple sources are attached.

    Kind regards!

    Source.zip

    From a discussion about expanding unit expressions with compound units I concluded that expanding derived units such as Newton, Watt, Volt, Tesla,... to SI base units is difficult in Maple.

    Unintentionally, I came across a rather simple solution for SI units.

    toSIbu := x -> x = Units:-Unit(simplify(x/Unit('kg'))*Unit('kg'));

    converts derived SI units to SI base units. It’s the inverse of what the units packages and simplify do (i.e. simplification to derived units).

    What makes it maybe more interesting: It also works, again unintentionally, on other units than SI units. If, one day, you come along an erg or a hartree or or a kyne and you cannot guess the SI units convert/units needs, try

    toSIbu(Unit('pound'));
    toSIbu(Unit('hp'));
    toSIbu(Unit('electron'));
    toSIbu(Unit('hartree'));
    toSIbu(Unit('bohr'));
    toSIbu(Unit('barye'));
    toSIbu(Unit('kyne'));
    toSIbu(Unit('erg'));
    toSIbu(Unit(mile/gal(petroleum)));

    Maybe handy one day when you do not trust AI or the web.


     

    NULL 

    toSIbu := x -> x = Units:-Unit(simplify(x/Unit('kg'))*Unit('kg')):
    toSIbu(Unit('N'));
    toSIbu(Unit('J'));
    toSIbu(Unit('W'));
    toSIbu(Unit('Pa'));
    toSIbu(Unit('C'));
    toSIbu(Unit('F'));
    toSIbu(Unit('S'));
    toSIbu(Unit('H'));
    toSIbu(Unit('T'));
    toSIbu(Unit('V'));
    toSIbu(Unit('Wb'));
    toSIbu(Unit('Omega'));
    toSIbu(Unit('lx'));
    toSIbu(Unit('lm'));
    toSIbu(Unit('degC'));
    toSIbu(Unit('rad'));
    toSIbu(Unit('sr'));

    Units:-Unit(N) = Units:-Unit(m*kg/s^2)

     

    Units:-Unit(J) = Units:-Unit(m^2*kg/s^2)

     

    Units:-Unit(W) = Units:-Unit(m^2*kg/s^3)

     

    Units:-Unit(Pa) = Units:-Unit(kg/(m*s^2))

     

    Units:-Unit(C) = Units:-Unit(A*s)

     

    Units:-Unit(F) = Units:-Unit(A^2*s^4/(m^2*kg))

     

    Units:-Unit(S) = Units:-Unit(A^2*s^3/(m^2*kg))

     

    Units:-Unit(H) = Units:-Unit(m^2*kg/(A^2*s^2))

     

    Units:-Unit(T) = Units:-Unit(kg/(A*s^2))

     

    Units:-Unit(V) = Units:-Unit(m^2*kg/(A*s^3))

     

    Units:-Unit(Wb) = Units:-Unit(m^2*kg/(A*s^2))

     

    Units:-Unit(`&Omega;`) = Units:-Unit(m^2*kg/(A^2*s^3))

     

    Units:-Unit(lx) = Units:-Unit(cd/m^2)

     

    Units:-Unit(lm) = Units:-Unit(cd)

     

    Units:-Unit(`&deg;C`) = Units:-Unit(K)

     

    Units:-Unit(rad) = Units:-Unit(m/m(radius))

     

    Units:-Unit(sr) = Units:-Unit(m^2/m(radius)^2)

    (1)

    NULL


     

    Download toSIbu.mw


    (All done with Maple 2024 without loading any package)

     

     

     

    Today in class, we presented an exercise based on the paper titled "Analysis of regular and chaotic dynamics in a stochastic eco-epidemiological model" by Bashkirtseva, Ryashko, and Ryazanova (2020). In this exercise, we kept all parameters of the model the same as in the paper, but we varied the parameter β, which represents the rate of infection spread. The goal was to observe how changes in β impact the system's dynamics, particularly focusing on the transition between regular and chaotic behavior.

    This exercise involves studying a mathematical model that appears in eco-epidemiology. The model is described by the following set of equations:

    dx/dt = rx-bx^2-cxy-`&beta;xz`/(a+x)-a[1]*yz/(e+y)

    dy/dt = -`&mu;y`+`&beta;xy`/(a+x)-a[2]*yz/(d+y)

    " (dz)/(dt)=-mz+((c[1 ]a[1])[ ]xz)/(e[]+x)+((c[1 ]a[2])[ ]yz)/(d+y)"

     

    where r, b, c, β, α,a[1],a[2], e, d, m, c[1], c[2], μ>0 are given parameters. This model generalizes the classic predator-prey system by incorporating disease dynamics within the prey population. The populations are divided into the following groups:

     

    • 

    Susceptible prey population (x): Individuals in the prey population that are healthy but can become infected by a disease.

    • 

    Infected prey population (y): Individuals in the prey population that are infected and can transmit the disease to others.

    • 

    Predator population (z): The predator population that feeds on both susceptible (x) and infected (y) prey.

     

    The initial conditions are always x(0)=0.2, y(0)=0.05, z(0)=0.05,  and we will vary the parameter β.;

     

    For this exercise, the parameters are fixed as follows:

     

    "r=1,` b`=1,` c`=0.01, a=0.36 ,` a`[1]=0.01,` a`[2]=0.05,` e`[]=15,` m`=0.01,` d`=0.5,` c`[1]=2,` `c[2]==1,` mu`=0.4."

    NULL

    Task (a)

    • 

    Solve the system numerically for the given parameter values and initial conditions with β=0.6 over the time interval t2[0,20000].

    • 

    Plot the solutions x(t), y(t), and  z(t) over this time interval.

    • 

    Comment on the model's predictions, keeping in mind that the time units are usually days.

    • 

    Also, plot the trajectory in the 3D space (x,y,z).

     

    restart

    r := 1; b := 1; f := 0.1e-1; alpha := .36; a[1] := 0.1e-1; a[2] := 0.5e-1; e := 15; m := 0.1e-1; d := .5; c[1] := 2; c[2] := 1; mu := .4; beta := .6

    sys := {diff(x(t), t) = r*x(t)-b*x(t)^2-f*x(t)*y(t)-beta*x(t)*y(t)/(alpha+x(t))-a[1]*x(t)*z(t)/(e+x(t)), diff(y(t), t) = -mu*y(t)+beta*x(t)*y(t)/(alpha+x(t))-a[2]*y(t)*z(t)/(d+y(t)), diff(z(t), t) = -m*z(t)+c[1]*a[1]*x(t)*z(t)/(e+x(t))+c[2]*a[2]*y(t)*z(t)/(d+y(t))}

    {diff(x(t), t) = x(t)-x(t)^2-0.1e-1*x(t)*y(t)-.6*x(t)*y(t)/(.36+x(t))-0.1e-1*x(t)*z(t)/(15+x(t)), diff(y(t), t) = -.4*y(t)+.6*x(t)*y(t)/(.36+x(t))-0.5e-1*y(t)*z(t)/(.5+y(t)), diff(z(t), t) = -0.1e-1*z(t)+0.2e-1*x(t)*z(t)/(15+x(t))+0.5e-1*y(t)*z(t)/(.5+y(t))}

    (1)

    ics := {x(0) = .2, y(0) = 0.5e-1, z(0) = 0.5e-1}

    {x(0) = .2, y(0) = 0.5e-1, z(0) = 0.5e-1}

    (2)

    NULL

    sol := dsolve(`union`(sys, ics), {x(t), y(t), z(t)}, numeric, range = 0 .. 20000, maxfun = 0, output = listprocedure, abserr = 0.1e-7, relerr = 0.1e-7)

    `[Length of output exceeds limit of 1000000]`

    (3)

    X := subs(sol, x(t)); Y := subs(sol, y(t)); Z := subs(sol, z(t))

    ``

    plot('[X(t)]', t = 0 .. 20000, numpoints = 350, title = "Trajectory of x(t)", axes = boxed, gridlines, color = ["#40e0d0"])

     

    plot('[Y(t)]', t = 0 .. 20000, numpoints = 350, title = "Trajectory", axes = boxed, gridlines, title = "Trajectory of y(t)", color = ["SteelBlue"])

     

    ``

    plot('[Z(t)]', t = 0 .. 20000, numpoints = 350, title = "Trajectory", axes = boxed, gridlines, title = "Trajectory of Z(t)", color = "Black"); with(DEtools)

     

    with(DEtools)

    DEplot3d(sys, {x(t), y(t), z(t)}, t = 0 .. 20000, [[x(0) = .2, y(0) = 0.5e-1, z(0) = 0.5e-1]], numpoints = 35000, color = blue, thickness = 1, linestyle = solid)

     

    Task (b)

    • 

    Repeat the study in part (a) with the same initial conditions but set β=0.61.

    NULL

    restart

    r := 1; b := 1; f := 0.1e-1; alpha := .36; a[1] := 0.1e-1; a[2] := 0.5e-1; e := 15; m := 0.1e-1; d := .5; c[1] := 2; c[2] := 1; mu := .4; beta := .61

    NULL

    sys := {diff(x(t), t) = r*x(t)-b*x(t)^2-f*x(t)*y(t)-beta*x(t)*y(t)/(alpha+x(t))-a[1]*x(t)*z(t)/(e+x(t)), diff(y(t), t) = -mu*y(t)+beta*x(t)*y(t)/(alpha+x(t))-a[2]*y(t)*z(t)/(d+y(t)), diff(z(t), t) = -m*z(t)+c[1]*a[1]*x(t)*z(t)/(e+x(t))+c[2]*a[2]*y(t)*z(t)/(d+y(t))}

    {diff(x(t), t) = x(t)-x(t)^2-0.1e-1*x(t)*y(t)-.61*x(t)*y(t)/(.36+x(t))-0.1e-1*x(t)*z(t)/(15+x(t)), diff(y(t), t) = -.4*y(t)+.61*x(t)*y(t)/(.36+x(t))-0.5e-1*y(t)*z(t)/(.5+y(t)), diff(z(t), t) = -0.1e-1*z(t)+0.2e-1*x(t)*z(t)/(15+x(t))+0.5e-1*y(t)*z(t)/(.5+y(t))}

    (4)

    NULL

    ics := {x(0) = .2, y(0) = 0.5e-1, z(0) = 0.5e-1}

    {x(0) = .2, y(0) = 0.5e-1, z(0) = 0.5e-1}

    (5)

    sol := dsolve(`union`(sys, ics), {x(t), y(t), z(t)}, numeric, range = 0 .. 20000, maxfun = 0, output = listprocedure, abserr = 0.1e-7, relerr = 0.1e-7)

    `[Length of output exceeds limit of 1000000]`

    (6)

    X := subs(sol, x(t)); Y := subs(sol, y(t)); Z := subs(sol, z(t))

    NULL

    plot('[X(t)]', t = 0 .. 20000, numpoints = 350, title = "Trajectory of x(t)", axes = boxed, gridlines, color = ["Blue"])

     

    plot('[Y(t)]', t = 0 .. 20000, numpoints = 350, title = "Trajectory of  Y(t)", axes = boxed, gridlines, color = "Red")

     

    plot('[Z(t)]', t = 0 .. 20000, numpoints = 350, title = "Trajectory of  Y(t)", axes = boxed, gridlines, color = "Black")

     

    NULL

    with(DEtools)

    DEplot3d(sys, {x(t), y(t), z(t)}, t = 0 .. 20000, [[x(0) = .2, y(0) = 0.5e-1, z(0) = 0.5e-1]], maxfun = 0, numpoints = 35000, color = blue, thickness = 1, linestyle = solid)

     

    The rate of the infection spread is affected by the average number of contacts each person has (β=0.6) and increases depending on the degree of transmission within the population, in particular within specific subpopulations (such as those in rural areas). A detailed epidemiological study showed that the spread of infection is most significant in urban areas, where population density is higher, while in rural areas, the rate of infection remains relatively low. This suggests that additional public health measures are needed to reduce transmission in densely populated areas, particularly in regions with high population density such as cities

    ``

    Download math_model_eco-epidemiology.mw

    This is another attempt to tell about one way to solve the problem of inverse kinematics of a manipulator.  
    We have a flat three-link manipulator. Its movement is determined by changing three angles - these are three control parameters. 1. the first link rotates around the black fixed point, 2. the second link rotates around the extreme movable point of the first link, 3. the third link − around the last point of the second link. These movable points are red. (The order of the links is from thick to thin.) The working point is green. For example, we need it to move along a circle. But the manipulator has one extra mobility (degree of freedom), that is, the problem has an infinite number of solutions. We have the ability to remove this extra degree of freedom mathematically. And this can also be done in an infinite number of ways.
    Let us give two examples where the same manipulator performs the same movement of the working point in different ways. In one case the last red point moves in a straight line, and in the other case it moves in an ellipse. The result is the same. In the corresponding program texts, the manipulator model is described by a system of nonlinear equations f1, f2, f3, f4, f5 relative to the coordinates of the ends of the links (very easy to understand). The specific additional connection that takes away one degree of freedom is highlighted in blue. Equation of a circle in red color.

    1.mw

    2.mw


    And as an elective. The same circle was obtained using a spatial 3-link manipulator with 5 degrees of freedom. In the last text, blue and red colors perform the same functions as in the previous texts.
    3.mw

     

    I'm excited to announce the creation of a new LinkedIn group, Maple Software Community! This group is dedicated to discussions about the use of Maple software and is designed to be a valuable resource for undergraduate and graduate students, researchers, and all Maple enthusiasts.

    By joining this community, you'll have the opportunity to:

    • Learn about upcoming events and workshops that can enhance your skills.
    • Stay informed on the latest projects that leverage Maple software.
    • Engage in discussions that explore the many uses of Maple across various fields.
    • Connect with Maple ambassadors and users worldwide who are eager to share their knowledge and experience.

    Whether you're a seasoned user or just starting out with Maple, your contributions to this group are welcome and encouraged. Let's build a thriving community together!


    Looking forward to seeing you there! 

    Maple Software Community

    I'm excited to share some valuable resources that I've found incredibly helpful for anyone looking to enhance their Maple skills. Whether you're just starting, studying as a student, or are a seasoned professional, these guides and books offer a wealth of information to aid your learning journey.

    Exploring Discrete Mathematics With Maple

    These materials are freely available and can be a great addition to your learning resources. They cover a wide range of topics and are designed to help users at all levels improve their Maple proficiency.

    You can add your own sources in a comment!

    Happy learning and I hope you find these resources as useful as I have!

    VerifyTools is a package that has been available in Maple for roughly 24 years, but until now it has never been documented, as it was originally intended for internal use only. Documentation for it will be included in the next release of Maple. Here is a preview:

    VerifyTools is similar to the TypeTools package. A type is essentially a predicate that a single expression can either satisfy or not. Analogously, a verification is a predicate that applies to a pair of expressions, comparing them. Just as types can be combined to produce compound types, verifications can also be combined to produce compund verifications. New types can be created, retrieved, queried, or deleted using the commands AddType, GetType (or GetTypes), Exists, and RemoveType, respectively. Similarly in the VerifyTools package we can create, retrieve, query or delete verifications using AddVerification, GetVerification (or GetVerifications), Exists, and RemoveVerification.

    The package command VerifyTools:-Verify is also available as the top-level Maple command verify which should already be familiar to expert Maple users. Similarly, the command VerifyTools:-IsVerification is also available as a type, that is,

    VerifyTools:-IsVerification(ver);

    will return the same as

    type(ver, 'verification');

    The following examples show what can be done with these commands. Note that in each example where the Verify command is used, it is equivalent to the top-level Maple command verify. (Also note that VerifyTools commands shown below will be slightly different compared to the Maple2024 version):

    with(VerifyTools):

    Suppose we want to create a verification which will checks that the length of a result has not increased compared to the expected result. We can do this using the AddVerification command:

    AddVerification(length_not_increased, (a, b) -> evalb(length(a) <= length(b)));

    First, we can check the existence of our new verification and get its value:

    Exists(length_not_increased);

    true

    GetVerification(length_not_increased);

    proc (a, b) options operator, arrow; evalb(length(a) <= length(b)) end proc

    For named verifications, IsVerification is equivalent to Exists (since names are only recognized as verifications if an entry exists for them in the verification database):

    IsVerification(length_not_increased);

    true

    On the other hand, a nontrivial structured verification can be checked with IsVerification,

    IsVerification(boolean = length_not_increased);

    true

    whereas Exists only accepts names:

    Exists(boolean = length_not_increased);

    Error, invalid input: VerifyTools:-Exists expects its 1st argument, x, to be of type symbol, but received boolean = length_not_increased

    The preceding command using Exists is also equivalent to the following type call:

    type(boolean = length_not_increased, verification);

    true

    Now, let's use the new verification:

    Verify(x + 1/x, (x^2 + 1)/x, length_not_increased);

    true

    Verify((x^2 + 1)/x, x + 1/x, length_not_increased);

    false

    Finally, let's remove the verification:

    RemoveVerification(length_not_increased);

    Exists(length_not_increased);

    false

    GetVerification(length_not_increased);

    Error, (in VerifyTools:-GetVerification) length_not_increased is not a recognized verification

    GetVerifications returns the list of all verifications known to the system:

    GetVerifications();

    [Array, FAIL, FrobeniusGroupId, Global, Matrix, MultiSet, PermGroup, RootOf, SmallGroupId, Vector, address, after, approx, array, as_list, as_multiset, as_set, attributes, boolean, box, cbox, curve, curves, dataframe, dataseries, default, default, dummyvariable, equal, evala, evalc, expand, false, float, function, function_bounds, function_curve, function_shells, greater_equal, greater_than, in_convex_polygon, indef_int, interval, less_equal, less_than, list, listlist, matrix, member, multiset, neighborhood, neighbourhood, normal, permute_elements, plot, plot3d, plot_distance, plotthing_compile_result, polynom, procedure, ptbox, range, rational, record, relation, reverse, rifset, rifsimp, rtable, set, sign, simplify, sublist, `subset`, subtype, superlist, superset, supertype, symbol, table, table_indices, testeq, text, true, truefalse, type, undefined, units, vector, verifyfunc, wildcard, xmltree, xvm]

    Download VerificationTools_blogpost.mw

    Austin Roche
    Software Architect
    Mathematical Software
    Maplesoft

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