## 145 Reputation

7 years, 262 days

## Another PDE to solve numerically....

Maple 2015

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).

## Checking a theorem about ultrahyperboli...

Maple

I have the following paper:

Now I wanted to check Fritz John's claim in the proof of Theorem 1.1, he says that equation (7) can be easily verified for case i=1,k=2.

Now at first I tried to calculate by hand, but it's just a lengthy calculation, so now I turned to maple to check its validity, I get that this claim is false, am I wrong in my code? if yes, then how to change it?

P.S

I changed between xi and x and eta and y.

In the following is the code:

 >
 (1)
 >
 >

 >
 (1)
 >
 >

## Recursive integral equation...

Maple 18

I want to find numerically the limit lim(y[m](t),m = infinity), do you have an idea how to do implement it in maple?

 >
 >

## An integral equation to solve ...

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.

## Solving PDE numerically...

Maple

I have the following PDE system to solve numerically and I am not sure how to use maple to solve it.

v_t = v_{xx} for 0<x<1 , t>0

v(x,0)=1

v_x(1,t)=-hv^4(1,t) (where h is some numerical number);

v_x(0,t)=0

To solve this pde numerically I need to use the following condition on v(1,t):

v(1,t) = 1-h*\int_{0}^t \theta_3(\tau)v(1,t-\tau)^4d\tau

this is the numerical boundary condition, where \theta_3 is Jacobi theta3 function.

I don't see how can I use maple for this numerical pde problem.

Here's my attempt at solution:

[code]

PDE := diff(v(x, t), t) = diff(v(x, t), x, x);

JACOBIINTEGRAL := int(JacobiTheta3(0, exp(-Pi^2*s))*v(1, t-s)^4, s = 0 .. t);

IBC := {&PartialD;(v(0, t))/&PartialD;(x) = 0, &PartialD;(v(1, t))/&PartialD;(x) = -0.65e-4*v(1, t)^4, v(x, 0) = 1};

pds := pdsolve(PDE, IBC, numeric, time = t, range = 0 .. 1, spacestep = 0.1e-2, timestep = 0.1e-2, numericalbcs = {v(1, t) = 1-0.65e-4*JACOBIINTEGRAL}, method = ForwardTimeCenteredSpace)

[/code]

But I get the next error message:

Error, (in pdsolve/numeric/process_IBCs) improper op or subscript selector

How to fix this or suggest me a better way to solve this pde numerically?

 5 6 7 Page 7 of 7
﻿