Re: [Help-gsl] ODE example, passing parameters

[Xuebin Wu]

The last parameter in func and jac should be (void *), not struct par * as
in you program.

However, I think it is just a warning, should not have a serious problem.

On Thu, Jun 10, 2010 at 8:02 AM, <address@hidden> wrote:

> Dear Sir or Madam,
>
> I slightly modified your ODE example and tried to pass multiple
> parameters. As you recommended I defined a structure in order to do that.
> But now I always get a warning in the following line:
> gsl_odeiv_system sys = {func, jac, 3, pz};
>
> where pz is a pointer to the structure that contains multiple paramters:
>
> "warning: initialization from incompatible pointer type"
>
> I get this warning twice. I guess the first time when I call the function
> "func" and the second time when I call "jac".
>
> Here is the code I use (is also attached):
>
> #include <stdio.h>
> #include <gsl/gsl_errno.h>
> #include <gsl/gsl_matrix.h>
> #include <gsl/gsl_odeiv.h>
>
>
>
>
> struct par{
>        double mu;
>        double om;
>        double de;
> };
>
> int
> func (double t, const double y[], double f[], struct par *pz)
> {
>
>  double mu=pz->mu;
>  double om=pz->om;
>  double de=pz->de;
>  //printf ("%.5e %.5e %.5e\n", pz->mu, pz->om, pz->de);
>
>  f[0] = om*y[1];
>  f[1] = -y[0] - mu*y[1]*(y[0]*y[0] - 1);
>  f[2] = de*y[1]*y[2];
>
>  return GSL_SUCCESS;
> }
>
> int
> jac (double t, const double y[], double *dfdy,
> double dfdt[], struct par *pz)
> {
>  double mu=pz->mu;
>  double om=pz->om;
>  double de=pz->de;
>  gsl_matrix_view dfdy_mat
>    = gsl_matrix_view_array (dfdy, 3, 3);
>  gsl_matrix * m = &dfdy_mat.matrix;
>  gsl_matrix_set (m, 0, 0, 0.0);
>  gsl_matrix_set (m, 0, 1, om);
>  gsl_matrix_set (m, 0, 2, 0.0);
>  gsl_matrix_set (m, 1, 0, -2.0*mu*y[0]*y[1] - 1.0);
>  gsl_matrix_set (m, 1, 1, -mu*(y[0]*y[0] - 1.0));
>  gsl_matrix_set (m, 1, 2, 0.0);
>  gsl_matrix_set (m, 2, 0, 0.0);
>  gsl_matrix_set (m, 2, 1, de*y[2]);
>  gsl_matrix_set (m, 2, 2, de*y[1]);
>
>  dfdt[0] = 0.0;
>  dfdt[1] = 0.0;
>  dfdt[2] = 0.0;
>  return GSL_SUCCESS;
> }
> /*
> void print_para(struct par *pz)
> {
>        printf ("%.5e %.5e %.5e\n", pz->mu, pz->om, pz->de);
> }
> */
>
> int
> main (void)
> {
>  FILE *fp;
>  fp = fopen("odetest.dat","w");
>  if(fp == NULL)
>   {
>      fprintf(stderr,"error: can't open odetest.dat!\n");
>      exit(EXIT_FAILURE);
>   }
>
>
>
>  const gsl_odeiv_step_type * T
>    = gsl_odeiv_step_rk8pd;
>
>  gsl_odeiv_step * s
>    = gsl_odeiv_step_alloc (T, 3);
>  gsl_odeiv_control * c
>    = gsl_odeiv_control_y_new (1e-6, 0.0);
>  gsl_odeiv_evolve * e
>    = gsl_odeiv_evolve_alloc (3);
>
>
>  struct par z, *pz;
>  pz=&z;
>  z.mu = 10;
>  pz->om = 1.45;
>  pz->de = 0.2;
>
>  printf ("%.5e %.5e %.5e\n", pz->mu, pz->om, pz->de);
>
>  //print_para(pz);
>
>  gsl_odeiv_system sys = {func, jac, 3, pz};
>
>  double t = 0.0, t1 = 100.0;
>  double h = 1e-6;
>  double y[3] = { 2.0, 2.0, 2.0 }; //initial cond
>
>  while (t < t1)
>    {
>        int status = gsl_odeiv_evolve_apply (e, c, s, &sys, &t, t1, &h, y);
>
>         if (status != GSL_SUCCESS)
>                break;
>
>         fprintf (fp,"%.5e %.5e %.5e %.5e\n", t, y[0], y[1], y[2]);
>
>    }
>
>  gsl_odeiv_evolve_free (e);
>  gsl_odeiv_control_free (c);
>  gsl_odeiv_step_free (s);
>
>
>  return 0;
> }
>
>
> Thanks in advance!
>
> Best,
> Willi
>
>
>
>
>
>
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