measuring rough scale of performance difference

experiments/fact/gauss.c

@@ -2,9 +2,9 @@
 #include <sys/time.h>
 
 int main(int argc, char**argv) {
-  unsigned long i, n, acc=0;
+  unsigned long long i, n, acc=0;
   struct timeval start, end;
-  sscanf(argv[1], "%lu", &n);
+  sscanf(argv[1], "%llu", &n);
 
 
   gettimeofday(&start, NULL);
@@ -12,7 +12,7 @@ int main(int argc, char**argv) {
     acc = acc + i;
   }
   gettimeofday(&end, NULL);
-  printf("%lu (%f milliseconds)\n", 
+  printf("%llu (%f milliseconds)\n", 
 	 acc,
 	 (1000.0*(end.tv_sec - start.tv_sec) + 
 	  ((end.tv_usec - start.tv_usec) / 1000.0) ));

experiments/fact/gauss.rkt

@@ -0,0 +1,18 @@
+#lang racket/base
+
+
+(define (gauss n)
+  (gauss-iter n 0))
+
+(define (gauss-iter n acc)
+  (if (= n 0)
+      acc
+      (gauss-iter (sub1 n) (+ acc n))))
+
+
+(define n (string->number (vector-ref (current-command-line-arguments) 0)))
+(define start (current-inexact-milliseconds))
+(define result (gauss n))
+(define end (current-inexact-milliseconds))
+
+(printf "~a (~a milliseconds)\n" result (- end start))