1 files changed, 70 insertions, 0 deletions
diff --git a/gsl-1.9/doc/examples/ode-initval.c b/gsl-1.9/doc/examples/ode-initval.c
new file mode 100644
index 0000000..8a8f794
--- /dev/null
+++ b/gsl-1.9/doc/examples/ode-initval.c
@@ -0,0 +1,70 @@
+#include <stdio.h>
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_matrix.h>
+#include <gsl/gsl_odeiv.h>
+
+int
+func (double t, const double y[], double f[],
+      void *params)
+{
+  double mu = *(double *)params;
+  f[0] = y[1];
+  f[1] = -y[0] - mu*y[1]*(y[0]*y[0] - 1);
+  return GSL_SUCCESS;
+}
+
+int
+jac (double t, const double y[], double *dfdy, 
+     double dfdt[], void *params)
+{
+  double mu = *(double *)params;
+  gsl_matrix_view dfdy_mat 
+    = gsl_matrix_view_array (dfdy, 2, 2);
+  gsl_matrix * m = &dfdy_mat.matrix; 
+  gsl_matrix_set (m, 0, 0, 0.0);
+  gsl_matrix_set (m, 0, 1, 1.0);
+  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));
+  dfdt[0] = 0.0;
+  dfdt[1] = 0.0;
+  return GSL_SUCCESS;
+}
+
+int
+main (void)
+{
+  const gsl_odeiv_step_type * T 
+    = gsl_odeiv_step_rk8pd;
+
+  gsl_odeiv_step * s 
+    = gsl_odeiv_step_alloc (T, 2);
+  gsl_odeiv_control * c 
+    = gsl_odeiv_control_y_new (1e-6, 0.0);
+  gsl_odeiv_evolve * e 
+    = gsl_odeiv_evolve_alloc (2);
+
+  double mu = 10;
+  gsl_odeiv_system sys = {func, jac, 2, &mu};
+
+  double t = 0.0, t1 = 100.0;
+  double h = 1e-6;
+  double y[2] = { 1.0, 0.0 };
+
+  while (t < t1)
+    {
+      int status = gsl_odeiv_evolve_apply (e, c, s,
+                                           &sys, 
+                                           &t, t1,
+                                           &h, y);
+
+      if (status != GSL_SUCCESS)
+          break;
+
+      printf ("%.5e %.5e %.5e\n", t, y[0], y[1]);
+    }
+
+  gsl_odeiv_evolve_free (e);
+  gsl_odeiv_control_free (c);
+  gsl_odeiv_step_free (s);
+  return 0;
+}