From 702dfc9cc3b7b323c3a42afaa41a51c41326e26d Mon Sep 17 00:00:00 2001
From: Racoonicorn <Racoonicorn@users.noreply.github.com>
Date: Fri, 9 Dec 2016 22:14:05 +0100
Subject: [PATCH] Create arithmetic_derivative.c

---
 arithmetic_derivative.c | 66 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 arithmetic_derivative.c

diff --git a/arithmetic_derivative.c b/arithmetic_derivative.c
new file mode 100644
index 0000000..ce8fd11
--- /dev/null
+++ b/arithmetic_derivative.c
@@ -0,0 +1,66 @@
+#define VER "0.3.1"
+#define N 20
+
+#include <stdio.h>
+
+int derivata (int n);
+void split (int value, int *a, int *b);
+
+int main () {
+	int n, res;
+	int sgn;
+	char again;
+	do {
+		sgn = 1;
+		do {
+			printf ("Inserisci numero:  ");
+			scanf ("%d", &n);
+		} while (0); // vanno messe condizioni
+		if (n < 0)
+			sgn = -1;
+		res = derivata (sgn * n);
+		res = sgn * res;
+		printf ("La derivata di %d è: %d", n, res);
+		getchar ();
+		printf ("\nAncora? [s/n] ");
+		scanf ("%c", &again);
+	} while (again == 's');
+	printf ("\n\n\nversion: %s", VER);
+}
+
+int derivata (int n){
+	int a = 1, b = 1;
+	switch (n) {
+		case 0:	return 1; break;
+		case 1: return 0; break;
+		default:
+			split (n, &a, &b);
+			if (a > 1 && b > 1){ // cioè non è primo
+				n = derivata(a) * b + a * derivata(b);
+			} else {
+				n = 1;
+			}
+			return n; 
+			break;
+	}
+}
+
+void split (int value, int *a, int *b) {
+	int i;
+	int j = 1; // res[0] è il numero di fattori di value
+	int res[N];
+	
+	for (i = 2; i <= value; i++) { //andrebbe ottimizzato
+		if (value % i == 0){
+			value = value / i;
+			res[j] = i;
+			j++;
+			i = 1;
+		}
+	}
+	res[0] = --j;
+	for (i = 1; i < res[0]; i++) {
+		*a = *a * res[i];
+	}
+	*b = res[res[0]];
+}