## 50 Reputation

19 years, 74 days

## maxfun limit exceeded in dsolve...

Maple

I'm trying to solve an ODE system from an IVP problem, but the error occurs: "Error, (in ...) cannot evaluate the solution further left of ..., maxfun limit exceeded (see ?dsolve,maxfun for details)"

I've already tried modifying the maxfun value but this did not work. I would like some suggestion.

Thank you

ODE_System.mw

## Increase speed of execution of the dsolv...

Maple 18

Is it possible to increase the execution speed of the dsolve command? For example, is it possible to increase speed with the use of Multithreaded tools?

## How to use an array/matrix as bcs for a ...

Maple

First: Is it possible to solve an pde equation/system where bcs are an array or matrix?

Second: Is it possible to get a discrete response in an array/matrix for this pde equation/system?

As an example I applied the heat conduction equation to a bar of 50 cm in length. Initially the bar has a uniform temperature field of 20ºC. The ends are maintained at a temperature of 0°C over time. I fixed a unitary thermal diffusivity.

restart:
k:=1:
pde:=k*diff(v(x,t),x\$2)=diff(v(x,t),t):
bc:={v(x,0)=20,v(0,t)=0,v(50,t)=0}:
sol:=pdsolve(pde,bc,numeric,time=t,range=0..50):
p1:=sol:-plot(t=0,numpoints=50,color=red):
p2:=sol:-plot(t=20,numpoints=50,color=blue):
p3:=sol:-plot(t=50,numpoints=50,color=red):
p4:=sol:-plot(t=150,numpoints=50,color=blue):
p5:=sol:-plot(t=300,numpoints=50,color=red):
plots[display]({p1,p2,p3,p4,p5});

I will put the two questions in another way:
I would like to insert the boundary conditions not as algebraic functions, but rather as array/matrix. It is possible?
I would like to result in not a procedure, but rather as array/matrix. It is possible?

## How to obtain a function that is defined...

Maple

I have a function g(x,t), which is the numerical result of a PDE.

How to calculate the function f (t), defined by:

f:=t->int(g(x,t),x=a..b)

I tried to calculate that way, but that did not work.

Thanks for the help.

## How to solve numerically a PDE system wi...

Maple

I have a PDE system, which has IBCs that involve the unknown functions of the system. This system describes the mechanical evolution of a material volume, where material boundaries vary (it is an open physical system with mass addition). This problem has an analytical solution, but I am looking for a numerical solution. I do not know how to solve this (actually, I do not know if that's possible). I made a few attempts and I did not succeed.

On the last attempt, pdsolve returned the following error message: "Error, (in pdsolve/numeric/process_PDEs) PDEs can only contain dependent variables with direct dependence on the independent variables of the problem, got {u(H(t), t)}".

PDE_SYS.mw  (I re-uploaded the file because there was an error)

Well, I'd like some help on that. Thank you.

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