ModSim ass3: Added log function.

modsim/ass3/methods.c

@@ -18,6 +18,11 @@ All functions return 0 upon success, or -1 when a computational error
 occurs (overflow, NaN or such)
 */
 
+#define LOG(t, y) { \
+    if( log_func != NULL ) \
+        log_func(t, y); \
+}
+
 int Euler(double t0, double t1, double dt, double *y0, double *y1, int N,
         f_ptr f, void *params) {
     int i, j, intervals = (t1 - t0) / dt;
@@ -27,6 +32,8 @@ int Euler(double t0, double t1, double dt, double *y0, double *y1, int N,
     for( j = 0; j < N; j++ )
         y1[j] = y0[j];
 
+    LOG(t0, y0)
+
     // Estimate for each interval
     for( i = 0; i < intervals; i++ ) {
         if( f(t, y1, dy, params) ) {
@@ -34,10 +41,11 @@ int Euler(double t0, double t1, double dt, double *y0, double *y1, int N,
             return -1;
         }
 
-        for( j = 0; j < N; j++ ) {
+        for( j = 0; j < N; j++ )
             y1[j] = y1[j] + dy[j] * dt;
+
         // Value can be printed/logged here
-        }
+        LOG(t, y1);
 
         t = t0 + i * dt;
     }
@@ -54,6 +62,8 @@ int RungeKutta2(double t0, double t1, double dt, double *y0, double *y1, int N,
     for( j = 0; j < N; j++ )
         y1[j] = y0[j];
 
+    LOG(t0, y0)
+
     // Estimate for each interval
     for( i = 0; i < intervals; i++ ) {
         if( f(t, y1, dy1, params) || f(t + dt, y1, dy2, params) ) {
@@ -61,10 +71,11 @@ int RungeKutta2(double t0, double t1, double dt, double *y0, double *y1, int N,
             return -1;
         }
 
-        for( j = 0; j < N; j++ ) {
+        for( j = 0; j < N; j++ )
             y1[j] = y1[j] + .5 * (dy1[j] + dy2[j]) * dt;
+
         // Value can be printed/logged here
-        }
+        LOG(t, y1);
 
         t = t0 + i * dt;
     }
@@ -81,6 +92,8 @@ int RungeKutta4(double t0, double t1, double dt, double *y0, double *y1, int N,
     for( j = 0; j < N; j++ )
         y[j] = y1[j] = y0[j];
 
+    LOG(t0, y0)
+
     // Estimate for each interval
     for( i = 0; i < intervals; i++ ) {
         if( f(t, y1, dy, params) ) {
@@ -121,9 +134,11 @@ int RungeKutta4(double t0, double t1, double dt, double *y0, double *y1, int N,
         for( j = 0; j < N; j++ ) {
             e4 = dy[j] * dt;
             y1[j] = y1[j] + (e1[j] + 2 * (e2[j] + e3[j]) + e4) / 6;
-            // Value can be printed/logged here
         }
 
+        // Value can be printed/logged here
+        LOG(t, y1);
+
         t = t0 + i * dt;
     }
 

modsim/ass3/methods.h

 typedef int (*f_ptr)(double t, double *y, double *dy, void *params);
+typedef void (*log_function)(double t, double *y);
+
+log_function log_func = NULL;
 
 int Euler(double t0, double t1, double dt, double *y0, double *y1, int N,
     f_ptr f, void *params);