Re: [Help-gsl] Setting maximum step size in ode solvers
"Bernard Siow" <[EMAIL PROTECTED]> writes:
> Thanks for the info. What happens to the actual step size, h, when the
> time interval, ti, is set to a value lower than h?
Read the source, Luke;)
,[gsl_odeiv_evolve_apply]
[...]
| double h0 = *h;
[...]
| if ((dt >= 0.0 && h0 > dt) || (dt < 0.0 && h0 < dt))
| {
| h0 = dt;
| final_step = 1;
| }
[...]
| *h = h0; /* suggest step size for next time-step */
[...]
`
Greetings,
Jochen
--
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(Part 3 you find in my messages before fall 2003.)
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RE: [Help-gsl] Setting maximum step size in ode solvers
Thanks for the info. What happens to the actual step size, h, when the time interval, ti, is set to a value lower than h? -Original Message- From: Brian Gough [mailto:[EMAIL PROTECTED] Sent: 13 June 2006 09:14 To: Bernard Siow Cc: help-gsl@gnu.org Subject: Re: [Help-gsl] Setting maximum step size in ode solvers Jochen Küpper writes: > "Bernard Siow" <[EMAIL PROTECTED]> writes: > > > Is it possible to set the maximum step size in the ode (ordinary > > > > differential equation) solvers? > > What's about using the T1 parameter to gsl_odeiv_evolve_apply? Yes, the second Van der Pol example in the ODE chapter of the GSL manual shows how to do something similar. -- Brian Gough Network Theory Ltd, Publishing the GSL Manual - http://www.network-theory.co.uk/gsl/manual/ ___ Help-gsl mailing list Help-gsl@gnu.org http://lists.gnu.org/mailman/listinfo/help-gsl
Re: [Help-gsl] Setting maximum step size in ode solvers
Jochen Küpper writes: > "Bernard Siow" <[EMAIL PROTECTED]> writes: > > > Is it possible to set the maximum step size in the ode (ordinary > > differential equation) solvers? > > What's about using the T1 parameter to gsl_odeiv_evolve_apply? Yes, the second Van der Pol example in the ODE chapter of the GSL manual shows how to do something similar. -- Brian Gough Network Theory Ltd, Publishing the GSL Manual - http://www.network-theory.co.uk/gsl/manual/ ___ Help-gsl mailing list Help-gsl@gnu.org http://lists.gnu.org/mailman/listinfo/help-gsl
Re: [Help-gsl] Setting maximum step size in ode solvers
"Bernard Siow" <[EMAIL PROTECTED]> writes: > Is it possible to set the maximum step size in the ode (ordinary > differential equation) solvers? What's about using the T1 parameter to gsl_odeiv_evolve_apply? ,[ (info "(gsl-ref)Evolution") ] | - Function: int gsl_odeiv_evolve_apply (gsl_odeiv_evolve * E, | gsl_odeiv_control * CON, gsl_odeiv_step * STEP, const | gsl_odeiv_system * DYDT, double * T, double T1, double * H, | double Y[]) | This function advances the system (E, DYDT) from time T and | position Y using the stepping function STEP. The new time and | position are stored in T and Y on output. The initial step-size | is taken as H, but this will be modified using the control | function C to achieve the appropriate error bound if necessary. | The routine may make several calls to STEP in order to determine | the optimum step-size. If the step-size has been changed the value | of H will be modified on output. The maximum time T1 is | guaranteed not to be exceeded by the time-step. On the final | time-step the value of T will be set to T1 exactly. ` > Also, I will have large and sudden changes in some of the parameters > and I think I will need to reset the step size to something small > whenever there is a large sudden change in parameters (predictable). Also set T1 to the predicted time of such a change and successively do whatever is necessary. Greetings, Jochen -- Einigkeit und Recht und Freiheithttp://www.Jochen-Kuepper.de Liberté, Égalité, FraternitéGnuPG key: CC1B0B4D (Part 3 you find in my messages before fall 2003.) ___ Help-gsl mailing list Help-gsl@gnu.org http://lists.gnu.org/mailman/listinfo/help-gsl
