## 10 Reputation

13 years, 110 days

## dsolve,numeric,stiff ode...

Hi Erik Postma,

Thank you for your response. I still thinking about the number ode's the rosenbrock solver can handle. Is there any information regarding the number of ode's. I am using a lot of ode's (200-300) and needs to be solved simultaneously.

When i call rosenbrock dsolve i.e dsolve, numeric, stiff=true, i am getting the following error:

Error, (in dsolve/numeric/SC/firststep) Unable to evaluate the partial derivatives of f(x,y) for stiff solution

But if i use less ode's (approx 100) , the solver works fine and i am getting the correct results from solver.

So, i am looking for information on the solver limitations/capacity?

## dsolve,numeric,stiff ode...

Hi Erik Postma,

Thank you for your response. I still thinking about the number ode's the rosenbrock solver can handle. Is there any information regarding the number of ode's. I am using a lot of ode's (200-300) and needs to be solved simultaneously.

When i call rosenbrock dsolve i.e dsolve, numeric, stiff=true, i am getting the following error:

Error, (in dsolve/numeric/SC/firststep) Unable to evaluate the partial derivatives of f(x,y) for stiff solution

But if i use less ode's (approx 100) , the solver works fine and i am getting the correct results from solver.

So, i am looking for information on the solver limitations/capacity?

## system ode's...

It's actually a pseudo steady state assumption so u(r,t) becomes u(r), where as the other ode v(r,t) is just an initial value problem since it doesn't have any derivatives of r.

Is there any way to solve a bvp and ivp (which are coupled) simultaneously to get the numerical solution?

## ode's...

u is not a function of t. u is only a function of r.

## thanks...

Thank you for your answer...Could you please give me more explanation on how to tackle this problem....i am not entirely sure about the bounadry conditions for the above mentioned sys1 and sys2.

## thanks...

Thank you for your answer...Could you please give me more explanation on how to tackle this problem....i am not entirely sure about the bounadry conditions for the above mentioned sys1 and sys2.

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