int
sys_driver (const gsl_odeiv_step_type * T,
const gsl_odeiv_system * sys,
double t0, double t1, double hstart,
double y[], double epsabs, double epsrel,
const char desc[])
{
/* This function evolves a system sys with stepper T from t0 to t1.
Step length is varied via error control with possibly different
absolute and relative error tolerances.
*/
int s = 0;
int steps = 0;
double t = t0;
double h = hstart;
gsl_odeiv_step * step = gsl_odeiv_step_alloc (T, sys->dimension);
gsl_odeiv_control *c =
gsl_odeiv_control_standard_new (epsabs, epsrel, 1.0, 0.0);
gsl_odeiv_evolve *e = gsl_odeiv_evolve_alloc (sys->dimension);
while (t < t1)
{
s = gsl_odeiv_evolve_apply (e, c, step, sys, &t, t1, &h, y);
if (s != GSL_SUCCESS)
{
gsl_test(s, "sys_driver: %s evolve_apply returned %d",
gsl_odeiv_step_name (step), s);
break;
}
if (steps > 1e7)
{
gsl_test(GSL_EMAXITER,
"sys_driver: %s evolve_apply reached maxiter at t=%g",
gsl_odeiv_step_name (step), t);
s = GSL_EMAXITER;
break;
}
steps++;
}
gsl_test(s, "%s %s [%g,%g], %d steps completed",
gsl_odeiv_step_name (step), desc, t0, t1, steps);
gsl_odeiv_evolve_free (e);
gsl_odeiv_control_free (c);
gsl_odeiv_step_free (step);
return s;
}
static VALUE rb_gsl_odeiv_step_info(VALUE obj)
{
gsl_odeiv_step *s;
char buf[256];
Data_Get_Struct(obj, gsl_odeiv_step, s);
sprintf(buf, "Class: %s\n", rb_class2name(CLASS_OF(obj)));
sprintf(buf, "%sSuperClass: %s\n", buf, rb_class2name(RCLASS_SUPER(CLASS_OF(obj))));
sprintf(buf, "%sType: %s\n", buf, gsl_odeiv_step_name(s));
sprintf(buf, "%sDimension: %d\n", buf, (int) s->dimension);
return rb_str_new2(buf);
}
void
test_odeiv_stepper (const gsl_odeiv_step_type *T, const gsl_odeiv_system *sys,
const double h, const double t, const char desc[],
const double ystart[], const double yfin[],
const double relerr)
{
/* tests stepper T with one fixed length step advance of system sys
and compares with given values yfin
*/
double y[MAXEQ] = {0.0};
double yerr[MAXEQ] = {0.0};
size_t ne = sys->dimension;
size_t i;
gsl_odeiv_step *step = gsl_odeiv_step_alloc (T, ne);
DBL_MEMCPY (y, ystart, MAXEQ);
{
int s = gsl_odeiv_step_apply (step, t, h, y, yerr, 0, 0, sys);
if (s != GSL_SUCCESS)
{
gsl_test(s, "test_odeiv_stepper: %s step_apply returned %d", desc, s);
}
}
for (i = 0; i < ne; i++)
{
gsl_test_rel (y[i], yfin[i], relerr,
"%s %s step(%d)",
gsl_odeiv_step_name (step), desc,i);
}
gsl_odeiv_step_free (step);
}
static VALUE rb_gsl_odeiv_step_name(VALUE obj)
{
gsl_odeiv_step *s = NULL;
Data_Get_Struct(obj, gsl_odeiv_step, s);
return rb_str_new2(gsl_odeiv_step_name(s));
}
static PyObject *
PyGSL_odeiv_step_name(PyGSL_odeiv_step *self, PyObject *args)
{
assert(PyGSL_ODEIV_STEP_Check(self));
return PyString_FromString(gsl_odeiv_step_name(self->step));
}
void
test_evolve_system (const gsl_odeiv_step_type * T,
const gsl_odeiv_system * sys,
double t0, double t1, double hstart,
double y[], double yfin[],
double err_target, const char *desc)
{
/* Tests system sys with stepper T. Step length is controlled by
error estimation from the stepper.
*/
int steps = 0;
size_t i;
double t = t0;
double h = hstart;
/* Tolerance factor in testing errors */
const double factor = 10;
gsl_odeiv_step * step = gsl_odeiv_step_alloc (T, sys->dimension);
gsl_odeiv_control *c =
gsl_odeiv_control_standard_new (err_target, err_target, 1.0, 0.0);
gsl_odeiv_evolve *e = gsl_odeiv_evolve_alloc (sys->dimension);
while (t < t1)
{
int s = gsl_odeiv_evolve_apply (e, c, step, sys, &t, t1, &h, y);
if (s != GSL_SUCCESS && sys != &rhs_func_xsin)
{
gsl_test(s, "%s evolve_apply returned %d",
gsl_odeiv_step_name (step), s);
break;
}
if (steps > 100000)
{
gsl_test(GSL_EFAILED,
"%s evolve_apply reached maxiter",
gsl_odeiv_step_name (step));
break;
}
steps++;
}
/* err_target is target error of one step. Test if stepper has made
larger error than (tolerance factor times) the number of steps
times the err_target */
for (i = 0; i < sys->dimension; i++)
{
gsl_test_abs (y[i], yfin[i], factor * e->count * err_target,
"%s %s evolve(%d)",
gsl_odeiv_step_name (step), desc, i);
}
gsl_odeiv_evolve_free (e);
gsl_odeiv_control_free (c);
gsl_odeiv_step_free (step);
}
