added code

slides/exemples/pow.c

+#include <stdio.h>
+
+double pow_naive(double x, int n) {
+    if (n == 0) {
+        return 1.0;
+    }
+    double res = x;
+    for (int i = 1; i < n; i++) {
+        res *= x;
+    }
+    return res;
+}
+
+double pow_rec(double x, int n) {
+    if (n == 0) {
+        return 1.0;
+    } else {
+        return x * pow_rec(x, n - 1);
+    }
+}
+
+double pow_eff(double x, int n) {
+    if (n == 0) {
+        return 1.0;
+    } else if (n % 2 == 0) {
+        double intermediate = pow_eff(x, n / 2);
+        return intermediate * intermediate;
+    } else {
+        return x * pow_eff(x, n - 1);
+    }
+}
+
+int main() {
+    double x = 2;
+    int n = 10000;
+    double y = 0;
+    for (int i = 0; i < 1000; ++i) {
+        // y += pow_eff(x, n);
+        y += pow_naive(x, n);
+    }
+
+    // printf("%lf^%d = %lf\n", x, n, pow_naive(x, n));
+    // printf("%d^%d = %lf\n", x, n, pow_rec(x, n));
+    // printf("%lf^%d = %lf\n", x, n, pow_eff(x, n));
+    printf("y = %lf\n", y);
+}