ModSim: Added max_steps parameter to bisection method.

modsim/ass2/bisection.c

 #include "bisection.h"
 
 double bisec(func_ptr f, double left, double right,
-        double epsilon, unsigned int *steps) {
-    double mid, fmid;
+        double epsilon, unsigned int *steps, unsigned int max_steps) {
+    double mid = left, fmid;
 
-    for( *steps = 0; fabs(right - left) > 2 * epsilon; (*steps)++ ) {
+    for( *steps = 0; (fabs(right - left) > 2 * epsilon)
+            && (!max_steps || (*steps < max_steps)); (*steps)++ ) {
         mid = (right + left) / 2;
 
         if( f(left) * (fmid = f(mid)) < 0 )
             right = mid;
         else if( f(right) * fmid < 0 )
             left = mid;
-        else
+        else {
+            (*steps)++;
             break;
+        }
     }
 
     return mid;

modsim/ass2/bisection.h

@@ -5,6 +5,6 @@
 #include "func_ptr.h"
 
 double bisec(func_ptr f, double left, double right,
-        double epsilon, unsigned int *steps);
+        double epsilon, unsigned int *steps, unsigned int max_steps);
 
 #endif

modsim/ass2/q2.c

@@ -20,7 +20,7 @@ int main(int argc, char *argv[]) {
     end = atoi(argv[2]);
 
     for( i = begin; i <= end; i++ ) {
-        bisection = bisec(&func, 0, 2, pow(10, -1.0 * i), &steps);
+        bisection = bisec(&func, 0, 2, pow(10, -1.0 * i), &steps, 100000);
         printf("zero point: %.30f for epsilon = 1e-%d (%d steps)\n", bisection, i, steps);
     }
 

modsim/ass2/q3.c

@@ -27,7 +27,7 @@ int main(int argc, char *argv[]) {
 
     for( i = begin; i <= end; i++) {
         epsilon = pow(10, -1.0 * i);
-        tmp= bisec(&f, 1, 2, epsilon, &steps);
+        tmp= bisec(&f, 1, 2, epsilon, &steps, 100000);
         printf("Sqrt(2) using bisection:      %.20f (%d steps; epsilon=%.0e)\n",
             tmp, steps, epsilon);