Hi, I solved some equations those days and get a group of data, namely, Data1. Then I want to get the function of the data, so I use the CurveFitting package of maple, and get the function easily (the function seems as a*x^3+b*x^2+c*x+d). But the function is not the one I really wanted, because it is hard to generate the complex curve (even the function is known) in some software. 

As I know, it is easily to generate some arcs in the software, so is there any way to fit a group of data with some piecewise of arcs?

 Best regards.

Data1:= [[.690499054221957, .109364306247567], [.679584570047867, 0.955093827253927e-1], [.668476295825779, 0.820785684569687e-1], [.657171143364362, 0.690714704619819e-1], [.645665768347822, 0.564884351571898e-1], [.633956566493958, 0.443305616055764e-1], [.622039668654294, 0.325997176601303e-1], [.609910934797136, 0.212985591645471e-1], [.597565946804089, 0.104305524003572e-1], [.585, 0], [.572208093323944, -0.998792942142104e-2], [.559184918035503, -0.195271676259796e-1], [.545924844835652, -0.286107087732754e-1], [.532421909264435, -0.372305667237386e-1], [.518669795218710, -0.453777271949494e-1], [.504661816411590, -0.530420942817277e-1], [.490390895570740, -0.602124307834357e-1], [.475849541144774, -0.668762917052363e-1], [.461029821255068, -0.730199502124052e-1]]

1. how to eliminate the diff(*(x,y,z),x) terms in an expression, "*" means any function which have independent variables x,y,z?

2. how to get the gradient of a vector, which should be a tensor?

Hi all,

I'm trying to create the 3D animation which can show the idea of rotating 2D function plot, such as:

with(plots):

display(seq(surfdata([seq([seq([x, cos(2*p*Pi*(1/25))*x^(1/2), -sin(2*p*Pi*(1/25))*x^(1/2)], x = 0 .. 4, .1)], p = 0 .. t)]), t = 1 .. 25), insequence = true);

But it's too inconvenient because of too many seq functions in this commond, is there any easier way to plot this animatiton?

Thank you.

I need to sort a list of vectors according to the alternating order defined as such: 

x <_alt y if x and y differ first in the ith place and

i is even and x_i > y_i or i is odd and x_i < y_i

(so that in even positions, the order is "flipped", and in odd positions, the order is the standard order).  

In this way, we arrive at 

0101 <_alt 0110 <_alt 0001 <_alt 1101 <_alt 1001

Below is an attempt...  

L:= [[ 0, 1, 0, 1], [0, 1, 1, 0], [0, 0, 0, 1], [1, 1, 0, 1], [1, 0, 0, 1]]

(in my actual code, my vectors will need to be of length 20).  

 Thank you for all of your help.  

Hello everyone,

I'm trying to solve system of ODE but it return this Error, (in fproc) unable to store 'YP[4]' when datatype=float[8]
How can this be corrected, see the worksheet YP.mw

Thanks.

Hi,

I am experiencing some problems with the plot3d command. It does not return a nice 3d-graph, but just a bunch of dashed lines. I have entered something like this:

with(plots):

plot3d(x*y,x=-1..1,y=-1..1);

I am using maple 17 on windows 7

Thanks in advance.

Int(ln(1+sqrt((x+1)/x)),x);

value(%);

Does not work.

Int(ln(2+sqrt((x+1)/x)),x);
value(%);

Works.

But with some effect,

Could this possibly be improved in the next release?

Hi,

Why does maple do this? For example:

>Digits := 4

>.67*((6918*(.856*11+1.08))/(42.2*2600^.36))^5;

=7.216 10^9

But with the Digit set to default it gives me:

>.67*((6918*(.856*11+1.08))/(42.2*2600^.36))^5;

=7.204144575 10^9

thanks!

I want to solve the int((y⁴+by²+c)^-1/2,y)-x and find y=h(x), where b and c are constants s.t. c>b²/4. Maple gives me complex Jacobi elliptic function as a result. But I am not sure that this integral has complex value. Am I doing something wrong or the result is really a complex valued function? Thanks.

Indeed my main question is: Plot y=y(u) where we have these two relations: int((y⁴+by²+c)^-1/2,y)=x and find y=h(x). Then evaluate int((h(x)-B)^-1/2,x)=u and find x=g(u). By using these relations plot y=y(u). :)

Here B is an arbitrary constant, but if necessary we can define a value for it. All the variables and constants are real.

I hope I manage to express myself. Thanks again.

Ok guys this is the problem i have a matrix wich is really the result of a semivariogram so it is like this 
thi is my semivariogram so i have to find the best model and fit it to it, i can't just throw a polynomial it has to be
spherical= h:= C((3/2)*x/a-(1/2)*x^3/a^3) 
expotencial=
Lineal= y:= p*x
or y:=p*x^a

so i want the maple to show me the variogram plot and the i select wich one of the models i will apply.
the problem is that i don't know how to apply the models so started something that could maybe lead to the values of C and A for the spherical and the xpotencial becouse the others too are easy.
------------------------------------------------------------------.--------------------------------------------------------
restart;
with(plots);
with(CurveFitting);
m3 := Matrix([[0, 0], [1, 2], [2, 5], [3, 7], [4, 10], [5, 14], [6, 15], [7, 15.4], [8, 15.8], [9, 16], [10, 16.4]]);
plot(m3);
Upsilon := C(1-exp(-x/a));
Upsilon := C((3/2)*x/a-(1/2)*x^3/a^3);
for C to 16 do
for a to 100 do
for x to 11 do
H := m3(x, 2);
R[C, a, x] := abs(Upsilon-H)
end do
end do
end do;
for r to 16 do
for j to 100 do
N[r, j] := sum(R[r, j, X], X = 1 .. 11);
if N[r, j] < 55 then
print(r, j)
end if
end do
end do;
k := 14*(3/2*((1/16)*xx)-(1/2)*xx^3/16^3);
multiple(plot, [m3, color = "Green"], [k, xx = 0 .. 11, color = "Blue"])
----------------------------------------------------------...................---------------------------------------
so in this code i rest the values of the model and the values of the matrix for differents C and a so i pick the min of the Sum to see wich C and a give me the min value but i didn't work quite well first is difficult to get the C and a and sometimes the new curve is just not similir to the semivariogram (Matrix) please help i tried 
k := NonlinearFit(C((3/2)*x/a-(1/2)*x^3/a^3), X, Y, x)
and 
k:=LeastSquares`(m3, v, curve = C*(1-exp(-x/a)))
but they don't let me because they aint linear on the parameters
please help 
if you are interested in this topic here is what i am trying to do but explained really well is for geological matters
http://www.kriging.com/PG1979/index.htm#Chapter_2+Part1

if want to help me use this matrix 
m3:= Matrix([[0, 0], [1, 1], [2, 3], [3, 5], [4, 7], [5, 8], [6, 9], [7, 10], [8, 10.5], [9, 10], [10, 9.8], [11, 9.8], [12, 10.5], [13, 10.89], [14, 11.2], [15, 10.6], [16, 9.85], [17, 9.45], [18, 9.77], [19, 10.15], [20, 10.7], [21, 10.04], [22, 10], [23, 10.85], [24, 10.7], [25, 10.94], [26, 10.81], [27, 10.33]])
for that matrix the spherical model is the best i know

goodbye

Very simple procedure:

Restart;

global a:=0.0065, R0:=1.225, T0:=273.16, gamma:=1.4, R:=287.04;

Spd :=proc(H, T1, IAS);

T:=T1+T0;

rho:=R0*(1-((a)/(T)*1000)^(4.26));

sigma:=T0/(T)*(1-(a/(T0)*H)^(5.26));

EAS:=sqrt((rho*IAS^(2))/(R0));

TAS:=EAS*sqrt(R0/(rho));

SpdSnd:=sqrt(gamma*R*T);

M:=TAS/(SpdSnd);

return M;

end proc;

Entering Spd(5000, 15, 400); with return I get

Spd(5000, 15, 400) in blue and not a numeric rsult.

Where am I wrong?

Martina

I have a table whose indices and entries are strings, as in:

    T := table(["green" = "gruen", "red" = "rot", "blue" = "blau"]);

Thus, T["green"] evaluates to "gruen" but T["asdf"] evaluates to T"asdf".

What is a good way to detect that "green" is a predefined index into the table but "asdf" is not?  I do it in a somewhat clumsy way, as in:

> has("green", [indices(T, 'nolist')]);
        true

> has("asdf", [indices(T, 'nolist')]);
        false

I suspect that there ought to be a less elaborate way of doing that.

I can't solve this problem, can someone explain me whats worng and how to fix it, here is what i've done:

with(plots);
with(DEtools);
sist := diff(x1(t), t) = -4*x1(t)+x2(t), diff(x2(t), t) = -x1(t)+7*x2(t);
    d                             d                          
   --- x1(t) = -4 x1(t) + x2(t), --- x2(t) = -x1(t) + 7 x2(t)
    dt                            dt                         


condi := [x1(0) = 0, x2(0) = 3], [x1(0) = 2, x2(0) = 1], [x1(0) = 7, x2(0) = 9];
        [x1(0) = 0, x2(0) = 3], [x1(0) = 2, x2(0) = 1],

          [x1(0) = 7, x2(0) = 9]
for i to 3 do sol[i] := dsolve({sist, condi[i]}, {x1(t), x2(t)}, numeric); gra := odeplot(sol[i], [x1(t), t], t = -1 .. 1); display(gra) end do;

http://www.gap-system.org/Manuals/doc/ref/chap50.html

which group do four differential electromagnetism belong to in library available in gap system? 

what is the order of the group?

do maple 17 have this group? how to show?

I'm currently having some difficulties in solving a system of differential equations numerically.

This is my code.