added friction

practical_work/vec2/util.c

+#include <stdlib.h>
+#include "util.h"
+
+double rand_to_range(double x0, double x1) {
+    double delta = x1 - x0;
+    double rescaled = (double)rand() / RAND_MAX * delta + x0;
+
+    return rescaled;
+}

practical_work/vec2/util.h

+#ifndef _UTIL_H_
+#define _UTIL_H_
+
+double rand_to_range(double x0, double x1);
+
+#endif