Re: [APM] Stiff ODE's

[John Hedengren]

Filipe,

I'd recommend that you try:

  % turns on coldstart (level 2)

  apm_option(server,app,'nlc.coldstart',2)

  apm(server,app,'solve')

  % turns off coldstart and time shifting

  apm_option(server,app,'nlc.coldstart',0)

  apm_option(server,app,'nlc.time_shift',0)

  apm(server,app,'solve')

This tries to break the problem down into simpler problems for initialization of very difficult problems.

We'll be concluding the training seminar this week tomorrow and reviewing methods to address some of the most challenging problems like initialization. If you'd like to join, please visit http://byu.webex.com with password: dyn2013. We'll start tomorrow morning at 8 AM, Mountain Time, USA. You are welcome to join us for this session.

Best regards,

John Hedengren

On Thu, May 2, 2013 at 11:37 AM, Filipe <gama....@gmail.com> wrote:

Hello,

Firstly, thank you very much for the opportunity of trying this wonderful soft. It's so easy to develop a model etc. I was waiting for these for some years!!!

I'm a chemical reactor professor at ist utl pt and I have usually stiff ode systems (mass balance and energy balance in chemical reactors) due to Arrhenius  temperature dependence of chemical reactions.

I tried all available solvers to me (1-3).

nlc.solver, 1 is usually the best between 1,2 and 3 solvers, but not enough. It can't solve the harder ones. By bad luck these are the most interesting.

Can you help me, showing some documentation (examples, etc.) how to overcome  this with apmonitor?

Thank's

virtualabs.ist.utl.pt

--
--
APMonitor user's group e-mail list.
- To post a message, send email to apmo...@googlegroups.com
- To unsubscribe, send email to apmonitor+...@googlegroups.com
- Visit this group at http://groups.google.com/group/apmonitor
 
---
You received this message because you are subscribed to the Google Groups "apmonitor" group.
To unsubscribe from this group and stop receiving emails from it, send an email to apmonitor+...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.