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hi every one..

how i solve numerically  couple equations which attached below .in solve this equation we must  starting from a very small value of V(voltage) with initial guesses for x1 and x3

near zero and using find root is noted that  the solution at this voltage step are used as initial guesses

for the next voltage step, and the process is repeated..


I am trying to integrate solutions to a set of differential equations I have obtained numerically but keep getting this error:

Error, (in solW) invalid input: subs received sol(r), which is not valid for its 1st argument

For simplicity, let's say I am interested in integrating the function W(r), which I obtain from 

sol := dsolve({eqns, ics}, numeric, abserr = 10^(-10), relerr = 10^(-10), range = ymin .. ymax)

I then use

solW := r -> subs(sol(r), W(y))

This gives me W(r) for any r in the range ymin to ymax. But I cannot do anything with this function. For example, 

int(solW(r),r=ymin..ymax) or plot(solW(r),r=ymin..ymax) give the error above. I know that I can plot the solutions using odeplot, but is there something analogous for integrating the solutions? 


I am considering the following PDE and I am getting an error, please suggest a better numerical method than the default one used in maple:


the PDE is:

u_{xx}u^3 - sin(xt)u_{tt} = u(x,t)

u(x, 0) = sin(x), (D[2](u))(x, 0) = cos(x), u(0, t) = cos(t), (D[1](u))(0, t) = sin(t)

Please suggest me a method that will also work for the following PDEs:

u^m* u_{xx} - sin(xt)u_{tt} = u^n

for m,n =0,1,2,3,... for the cases m=n and m not equal n

Here's the code:


pde := u(x, t)^3*(diff(u(x, t), x, x))-sin(x*t)*(diff(u(x, t), t, t)) = u(x, t);

u(x, t)^3*(diff(diff(u(x, t), x), x))-sin(x*t)*(diff(diff(u(x, t), t), t)) = u(x, t)


ibc := u(x, 0) = sin(x), (D[2](u))(x, 0) = cos(x), u(0, t) = cos(t), (D[1](u))(0, t) = sin(t);

u(x, 0) = sin(x), (D[2](u))(x, 0) = cos(x), u(0, t) = cos(t), (D[1](u))(0, t) = sin(t)


pds := pdsolve(pde, [ibc], numeric, time = t, range = 0 .. 1, spacestep = 0.1e-1)

module () local INFO; export plot, plot3d, animate, value, settings; option `Copyright (c) 2001 by Waterloo Maple Inc. All rights reserved.`; end module


pds:-plot3d(u(x, t), t = 0 .. 1, x = 0 .. 1, labels = [t, x, u(x, t)], labelfont = [times, bold, 20], axesfont = [times, bold, 16])

Error, (in pdsolve/numeric/plot3d) unable to compute solution for t>HFloat(0.0):
Newton iteration is not converging





I have an arrays of data. One for x values, and one for y values. How can I obtain a numerical integration of y for a range of x values?

I have tried defining a function of X using ArrayInterpolation(x,y,X) and then calling evalf(Int(f,xmin..xmax)) but that gives an error message. (I don't seem to be able to paste into this window) The error message says

"Error, invalid input: evalf expects its 2nd argument, n, to be of type posint, but received numeric."

I thought I was using a form of the equation right from the help system.

I also tried the 2D version of integration, but it returns the difference of my limits times my function name.

I aslo tried AdaptiveQuadrature, but I can't get that to work either.

-Mike McDermott

Newbie Maple user



I want to solve numerically the nonlinear pde:


u_x+u_t - (u_{xt})^2 = u(x,t)


which method do you propose me to use with maple? (I don't mine about which boundary conditions to be used here).


I have the following integral equation to solve numerically:


v(x,t)=1 - h*\int_0^t JacobiTheta0(1/2x , \pi i s) v^4(1,t-s)ds

where h is a numerical parameter, and v(1,t) = 1-h*\int_0^t \theta_3(r)v^4(1,t-r)dr (theta3 is Jacobi theta3 function).


So I want to use an iteration method that will converge numerically to the solution, where v(1,0)=1.

How to use maple for this?

I want also to find the rate of convergence to the numerical solution.

 edit: I should note that v(x,0)=1, even though it's implied from v(x,t) above.



sorry for that question, i'm a beginner in maple but i think my question is not as simple.

So, i want to solve numerically this first equation :

but the second term is present only if k*(U*t-x)>μc*m*g  (stick-slip problem)

initial conditions : U=1m/s; x=0m; k=10 for example

My problem is simple, i don't know how to use conditional statement for such an ode in maple.

I've tried > Xr := U*t-x;
> k := 10; m := 1; g := 10; mu := .2;
> if k*Xr > mu*m*g then ode1 := m*(diff(x(t), t, t)) = k.Xr-mu*m*g else ode1 := m*(diff(x(t), t, t)) = k.Xr end if;

But, of course, too optimistic.

Thank to anyone who will solve that (isuppose) simple problem



This is the system of equations in term of sin and cos. I have used the command "solve" in Maple but it yielded only 2 solutions. I've tried to use with(RealDomain): It yielded more solutions but most of them were wrong.



f1 := -8100+(-30+70*cos(t1)-40*cos(t2))^2+(-70*sin(t1)+40*sin(t2))^2

f2 := (-20-80*cos(t3))^2+(-15+70*cos(t1)+10*cos(t1+t))^2+(-70*sin(t1)-10*sin(t1+t)+80*sin(t3))^2-5625

f3 := (-20-80*cos(t3))^2+(15+40*cos(t2)+10*cos(t1+t))^2+(-40*sin(t2)-10*sin(t1+t)+80*sin(t3))^2-5625

f4 := 10*cos(t1+t)*(30-70*cos(t1)+40*cos(t2))-10*sin(t1+t)*(70*sin(t1)-40*sin(t2))


Anybody know how to solve this system of equations to get the full set of roots?

Thank you very much in advance.

Dear Friends:

I am currently working on a calculation for phase velocity of acoustic waves and don’t get along.  

My equation has the following form:

equ := tan( (31 / 20000) * sqrt( -9610000/c^2 + 1) / Pi) / tan((961/1260000) * sqrt( -39690000/c^2 + 1)/ P i) = -(1191640000/63)*sqrt(-9610000/c^2 + 1)*sqrt (-39690000/c^2 + 1)/ (c^2*(19220000/c^2 - 1)^2)

Using ‘sol = solve(equ,c)’ returns

sol := 96100* RootOf(1 + (400000000 * Pi^2 * RootOf(40320000000000000000 * Pi^4 * tan(_Z)*_Z^4256000000000000 * Pi^3 * csgn(_Z) * _Z^3 * tan((1/157500) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) / Pi) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) -96868800000000 * Pi^2 * tan(_Z) * _Z^2 + 615040000 * Pi * csgn(_Z) * _Z * tan((1/157500) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167) / Pi ) * sqrt(24806250000 * Pi^2 * _Z^2 - 45167)+58181823 * tan(_Z))^2 - 961)* _Z^2)

c should be in a range of 13,000.

Two questions:

1) How can I deal with _Z?

2) Any suggestion how I can calculate ‘c’? Maybe numerical?

I am relative new in maple…

Many thanks!



     I'm trying to numerically solve a PDE in Maple for different boundary conditions, however I'm having trouble even getting Maple to numerically solve it for simple boundary conditions.

I have cylindrical coordinates, r, z, theta, and I treat r = r(z, theta) for convenience to plot my solution surface. The initial coundary condition is that at z = epsilon (z = 0 is singular) , r = constant and of course r is periodic in theta. This is just a circle, and the analytical solution is know to be a half-sphere  r = sqrt(R^2 - z^2). I entered my initial boundary conditions into Maple, but it doesn't like the periodic one

IBC := { r(epsilon, theta) = R - epsilon__r,
              r(z, 0) = r(z, 2*Pi) };

  indepvars = [z, theta],
  time = z,
  range = 0..2*Pi);
Error, (in pdsolve/numeric/par_hyp) Incorrect number of boundary conditions, expected 2, got 1

I'm not sure how to make this work, and then generalize it to more arbitrary intial slices r(epsilon, theta) = f(theta).

Here's the attached worksheet,

Any help is appreciated,


Any suggestions (or perhaps related examples?) illustrating how I might numerically solve for f(t) in the following non-linear integral equation?  In Fortran, I would start with a guess f(t)=T0, and then search in the neighborhood for a minimum (in the error), but I am not familiar with numerical searches and methods in Maple.  Thank you for any suggestions or leads.

(a,b,... etc are all real)

T__0 := 298.

`ΔT` := 25.

0 < beta and beta <= 1


f*t = T[0]+`&Delta;T`*[1-exp(-a(int(exp(-b/f(y)), y = y[1] .. t))^beta)]






Good day everyone,

Please I do get numerical output/values in this solution

Best regards

I have to solve a numerical problem and I was wondering how to make maple treat very small numbers as zero. Say I do not care about anything less than 10^-5, so maple should treat all such numbers as zero. How to set this behaviour for the entire session? Thanks!


I have a system of pdes and solved numerically using pdsolve (numeric) command.

The system consists of four first order partial differentia equations.

for example u(x,t), R(x,t)....

what command should I give to the Maple and get the graph of u(x,t) at a specific point x_0?

For example, I need a plot for u(30,t).

Is it possible with the maple plot?

I really appreciate your help.

Thank you for reading this post. :)


I have a problem solving a system of PDEs.

The system of PDEs are

PDE01 := -(l^2+1^2)*(diff(v(l, t), t))+(l^2+1^2)*(diff(R(l, t), l, l))+4*l*(diff(R(l, t), l))+4*l*v(l, t)/(l^2+1^2)^(1/4)-6*R(l, t)/(l^2+1^2)+(l^2+1^2)^(1/2)*(-1.1+sqrt(.1))^2*sqrt(24)*u(l, t) = 0

PDE02 := diff(R(l, t), t) = v(l, t)

PDE03 := diff(u(l, t), t)-sqrt((1.1^2-1)/1.1^2)*(diff(u(l, t), l))-2*l*sqrt(1.1^2-1)*u(l, t)/(l^2+1^2) = 0

the initial condisions are

v(l, 0) = 0, R(l, 0) = 0, u(l, 0) = sqrt((l^2+1^2)^(1/2))*10^(-5)*exp(-(l-10)^2/.5^2)

and the BCs are

bdry00 := {((30^2+1^2)/30^2)^(1/4)*v(-30, t) = -((30^2+1^2)/30^2)^(1/2)*(D[1](R))(-30, t), ((30^2+1^2)/30^2)^(1/4)*v(30, t) = -((30^2+1^2)/30^2)^(1/2)*(D[1](R))(30, t), u(-30, t) = sqrt(30^2+1^2)*10^(-5)*exp(-40000), u(30, t) = sqrt(30^2+1^2)*10^(-5)*exp(-10000)}

to solve the system,

I enter

pde := pdsolve({PDE01, PDE02, PDE03}, {bdry00, init00}, time = t, numeric, range = -30 .. 30, timesstep = 1/60, spaceste = 1/254)

then, I failed to get the result constantly.

I tried several cases changing the initial conditions...

Can you let me know what I am doing wrong?


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