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+/* Copyright (C) 2016 - IIT Bombay - FOSSEE
+
+ This file must be used under the terms of the CeCILL.
+ This source file is licensed as described in the file COPYING, which
+ you should have received as part of this distribution. The terms
+ are also available at
+ http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
+ Author: Siddhesh Wani
+ Organization: FOSSEE, IIT Bombay
+ Email: toolbox@scilab.in
+*/
+
+//Function for solving ODEs using GSL library
+
+#include "ode.h"
+#include "types.h"
+#include <gsl/gsl_errno.h>
+#include <gsl/gsl_matrix.h>
+#include <gsl/gsl_odeiv2.h>
+
+
+void dodea(double *initial_value, double start_time, double end_time, \
+ char *ode_function, double nequs, double eps_abs, double eps_rel, \
+ double step_size, int *params, double *out)
+{
+ double t = start_time;
+ //Initialise output to initial state
+ int counter = 0;
+ for (counter = 0; counter<nequs;counter++)
+ {
+ out[counter] = initial_value[counter];
+ }
+
+ //Setup ODE related parameters
+ gsl_odeiv2_system sys = {ode_function, NULL, 2, params};
+
+ gsl_odeiv2_step *s = gsl_odeiv2_step_alloc (gsl_odeiv2_step_rkf45, nequs);
+ gsl_odeiv2_control *c = gsl_odeiv2_control_y_new (eps_abs, eps_rel);
+ gsl_odeiv2_evolve *e = gsl_odeiv2_evolve_alloc (nequs);
+
+ while(t < end_time)
+ {
+ gsl_odeiv2_evolve_apply_fixed_step (e, c, s, &sys, &t, step_size, out);
+ }
+
+ gsl_odeiv2_evolve_free (e);
+ gsl_odeiv2_control_free (c);
+ gsl_odeiv2_step_free (s);
+}