## 10 Reputation

13 years, 106 days

## dsolve,numeric,stiff=true...

Maple

Hello all,

Is any anyone know how good is maple numeric stiff ode solver (stiff=true) ? What i mean is how many stiff ode's it can handle at a given time. I am having a hardtime solving a system of ode's (say 300 stiff ode's). Is there any other numeric stiff ode solver in maple that can handle large number of ode's?

I used islode advanced numeric solver for stiff ode's and it also has some limitations on the number of ode's and moreover it is slow.

## Analytical Solution...

Maple

Hi all,

I am trying to solve a system of pde's to get an analytical solution in maple. here's the system:

pde1:=diff(Ti(r,t),t)=(1/r)*diff(r*diff(Ti(r,t),r),r);

bc1:=Ti(r,0)=1,D1(Ti)(0,t)=0,D1(Ti)(1,t)=D1(To)(1,t);

pde2:=diff(To(r,t),t)=(1/r)*diff(r*diff(To(r,t),r),r);

bc2:=To(r,0)=0,D1(To)(1,t)=D1(Ti)(1,t),D1(To)(1.5,t)=0;

sys:=[pde1,pde2,bc1,bc2];

sol:=pdsolve(pde);

Error, (in pdsolve/sys) the input system...

## solving ode's and nonlinear algebraic eq...

Maple

Hi all,

I am trying to solve a system of equations- ode's and nonliear algebraic equations numerically. The maple dsolve actually solves this type of system but the problem is it is taking lot of time to solve. I think it is not solving the algebraic equation numerically.

i am using dsolve as: dsolve({eqs,ic},type=numeric,output=listprocedure).

Is there any other way to specify maple dsolve to solve all equations including algebraic numerically?

## System of ode's...

Hi all,

I want to solve the following 2 odes simultaneously:

ode1:=(1/r^2)*diff(r^2*diff(u(r),r),r) =v(t); (#boundary value problem with 2 boundaries)

ode2:= diff(v(t),t)=u(r); (#initial value problem)

with conditions

IBC={u(0.2)=1,u(0)=0.5,v(0)=0.01}

I am getting error if i use dsolve/numeric. Is there any way/method to solve these numerically using maple packages like dsolve/fsolve...

Thanks,

## Numerical Stability...

Maple

Hi all,

I am having a very hard time with numerical stability. I am solving system of ode's (7-coupled ode's) using dsolve(stiff) and then using spline function for interpolation and finally solving system of pde's (2-coupled pde's) using pdsolve for one time step and solving all again for the next step. the solution is not stable and it requires very fine/small time step. Is there any procedure/method to improve the stability?

What is the stability criteria of dsolve...

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