ModSim ass4 taddeus: Inserted print statements and cleaned up code.

modsim/ass4_taddeus/vibstring/seq.c

@@ -3,20 +3,17 @@
 #include <string.h>
 #include <math.h>
 
-#define DEBUG
-
-/*
- *
- */
-double **init_sinus(double l, double dx, double n, int *steps) {
-    double **y;
+double **create_y(int steps) {
+    double **y = (double **)malloc(steps * sizeof(double *));
     int i;
 
-    *steps = (int)ceil(l / dx);
-    y = (double**)malloc(3 * *steps * sizeof(double));
+    if( y == NULL ) {
+        puts("Error: could not allocate sufficient memory.");
+        exit(EXIT_FAILURE);
+    }
 
-    for( i = 0; i < *steps; i++ )
-        y[i][0] = sin(n * M_PI * i * dx / l);
+    for( i = 0; i < steps; i++ )
+        y[i] = (double *)malloc(3 * sizeof(double));
 
     return y;
 }
@@ -24,69 +21,138 @@ double **init_sinus(double l, double dx, double n, int *steps) {
 /*
  *
  */
-double **init_plucked(double l, double dx, double xp, int *steps) {
-    double **y, x;
-    int i;
+void init_sinus(double **y, int steps, double l, double dx, double n) {
+    for( int i = 0; i < steps; i++ )
+        y[i][0] = sin(n * M_PI * i * dx / l);
 
-    *steps = (int)ceil(l / dx);
-    y = (double**)malloc(3 * *steps * sizeof(double));
+    // The string is attached at both ends
+    y[0][2] = y[0][1] = y[0][0];
+    y[steps - 1][2] = y[steps - 1][1] = y[steps - 1][0];
+}
+
+/*
+ *
+ */
+void init_plucked(double **y, int steps, double l, double dx, double xp) {
+    double x;
 
-    for( i = 0; i < *steps; i++ ) {
+    for( int i = 0; i < steps; i++ ) {
         x = i * dx;
         y[i][0] = x < xp ? x / xp : (l - x) / (l - xp);
     }
 
     // The string is attached at both ends
     y[0][2] = y[0][1] = y[0][0];
-    y[*steps - 1][2] = y[*steps - 1][1] = y[*steps - 1][0];
-
-    return y;
+    y[steps - 1][2] = y[steps - 1][1] = y[steps - 1][0];
 }
 
-void iterate(double **y, int steps, double dx, double T) {
+#define DEBUG
+
+#ifdef DEBUG
+#define PRINT_FORMAT "%10f" // More readable print format (outlined)
+#else
+#define PRINT_FORMAT "%f" // Raw data, aplittable by space character
+#endif
+
+void iterate(double **y, int string_steps, double dx, int time_steps,
+        double dt, double theta, int verbose_level) {
     double x;
-    int i, prev = 0, current = 1, next = 2;
+    int i, t, prev = 0, current = 1, next = 2;
 
     // Calculate the position over the entire string at time dt using the
     // position at t = 0 and the information that y(x, -dt) == y(x, dt)
-    for( i = 2; i < steps; i++ ) {
+    for( i = 1; i < string_steps - 1; i++ ) {
         x = i * dx;
-        y[i][1] = y[i][0] + .5 * T * T * (y[i-1][0] - 2 * y[i][0] + y[i-1][0]);
+        y[i][1] = y[i][0] + .5 * theta * theta * (y[i-1][0] - 2 * y[i][0]
+                  + y[i+1][0]);
+    }
+
+    // Print init states
+    if( verbose_level ) {
+        for( t = 0; t < 2; t++ ) {
+            printf(PRINT_FORMAT, t * dt);
+
+            for( i = 0; i < string_steps; i++ )
+                printf(" " PRINT_FORMAT, y[i][t]);
+
+            puts("");
+        }
     }
 
     // Iterate over the length of the string
-    for( i = 1; i < steps - 1; i++ ) {
-        y[i][next] = 2 * y[i][current] - y[i][prev]
-            + T * T * (y[i-1][current] - 2 * y[i][current] + y[i+1][current]);
+    for( t = 0; t < time_steps; t++ ) {
+        if( verbose_level )
+            printf(PRINT_FORMAT " " PRINT_FORMAT, t * dt, y[0][next]);
+
+        for( i = 1; i < string_steps - 1; i++ ) {
+            y[i][next] = 2 * y[i][current] - y[i][prev] + theta * theta
+                * (y[i-1][current] - 2 * y[i][current] + y[i+1][current]);
+
+            if( verbose_level )
+                printf(" " PRINT_FORMAT, y[i][next]);
+        }
+
+        if( verbose_level )
+            printf(" " PRINT_FORMAT "\n", y[string_steps - 1][next]);
 
         prev = current;
         current = next;
         next = (next + 1) % 3;
     }
 
+    // Free allocated memory
+    for( i = 0; i < string_steps; i++ )
+        free(y[i]);
+
     free(y);
 }
 
 int main(int argc, const char **argv) {
-    int steps;
-    double **(*method)(double, double, double, int*);
-
-    if( argc < 5 ) {
-        printf("Usage: %s INIT_METHOD L DX T N|XP\n", argv[0]);
+    int steps, verbose_level = 1;
+    void (*init_method)(double **, int, double, double, double);
+    double **y, t, dt, l, dx, theta, constant;
+
+    /*
+     * Argv:
+     * 0: ./seq
+     * 1: sinus/plucked
+     * 2: t
+     * 3: dt
+     * 4: l
+     * 5: dx
+     * 6: theta
+     * 7: n/xp (init constant)
+     * 8: verbose level
+     */
+    if( argc < 8 ) {
+        printf("Usage: %s METHOD TIME DT LENGTH DX THETA N|XP [ VERBOSE_LEVEL ]\n",
+               argv[0]);
         return EXIT_FAILURE;
     }
 
     if( !strcmp(argv[1], "sinus") ) {
-        method = init_sinus;
+        init_method = init_sinus;
     } else if( !strcmp(argv[1], "plucked") ) {
-        method = init_plucked;
+        init_method = init_plucked;
     } else {
-        printf("Unknown method '%s'.\n", argv[1]);
+        printf("Unknown initialization method '%s'.\n", argv[1]);
         return EXIT_FAILURE;
     }
 
-    iterate((*method)(atof(argv[2]), atof(argv[3]), atof(argv[5]), &steps),
-            steps, atof(argv[3]), atof(argv[4]));
+    t = atof(argv[2]);
+    dt = atof(argv[3]);
+    l = atof(argv[4]);
+    dx = atof(argv[5]);
+    theta = atof(argv[6]);
+    constant = atof(argv[7]);
+
+    if( argc == 9 )
+        verbose_level = atoi(argv[8]);
+
+    y = create_y(steps = (int)ceil(l / dx));
+
+    (*init_method)(y, steps, l, dx, constant);
+    iterate(y, steps, dx, (int)ceil(t / dt), dt, theta, verbose_level);
 
     return EXIT_SUCCESS;
 }