From: W. Trevor King <wking@tremily.us>
Date: Tue, 12 Feb 2013 22:00:20 +0000 (-0500)
Subject: one_gaussian_bump.c: Prepare for alternative integrators
X-Git-Url: http://git.tremily.us/?a=commitdiff_plain;h=7f86ecf6f585b644cfe7b338aa9adca144fb9b6a;p=assignment-template.git

one_gaussian_bump.c: Prepare for alternative integrators
---

diff --git a/one_gaussian_bump.c b/one_gaussian_bump.c
index 792ca64..bc67e44 100644
--- a/one_gaussian_bump.c
+++ b/one_gaussian_bump.c
@@ -68,6 +68,9 @@ typedef struct system_struct {
 	void *dx_dt_state;      /* gaussian_state_t, etc. */
 } system_t;
 
+/* function type for integration */
+typedef void (*step_fn_t)(state_t *state, system_t *system, double dt);
+
 /* Potential:    V(r) = 1/2 kb^2 exp(-r^2/b^2) */
 double gaussian_energy(gaussian_state_t *state, double x, double y)
 {
@@ -123,7 +126,7 @@ double single_gaussian_energy(state_t *state, void *system)
 	return kinetic + potential;
 }
 
-void step(state_t *state, system_t *system, double dt)
+void euler_step(state_t *state, system_t *system, double dt)
 {
 	double *dx_dt = NULL;
 	size_t i;
@@ -213,6 +216,7 @@ int main(int argc, char **argv) {
 	double x[4] = {3.5, 0, 0, 0};
 	system_t system = {};
 	gaussian_state_t gaussian = {};
+	step_fn_t step_fn = &euler_step;
 
 	state.x = (double *)x;
 	state.n = sizeof(x) / sizeof(double);
@@ -228,7 +232,7 @@ int main(int argc, char **argv) {
 
 	print_state(&state, &system);
 	while (state.t < t_max) {
-		step(&state, &system, dt);
+		(*step_fn)(&state, &system, dt);
 		print_state(&state, &system);
 	}
 	return 0;