diff --git a/Makefile b/Makefile
index ce05190..28c6153 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,5 @@
 all:
-	gcc -Wall -ansi -pedantic -o vocal main.c dsp.c utils.c -lm -w -O3 -funroll-loops -fno-rtti -ffast-math -fno-stack-protector -ffunction-sections -funsafe-math-optimizations -fno-trapping-math
+	gcc -Wall -pedantic -o vocal main.c dsp.c utils.c -lm -O3 -funroll-loops -w -ffast-math -fno-stack-protector -ffunction-sections -funsafe-math-optimizations -fno-trapping-math
 
 clean:
 	rm vocal
diff --git a/main.c b/main.c
index b572bb7..b8a1b4e 100644
--- a/main.c
+++ b/main.c
@@ -19,9 +19,43 @@
 
 typedef enum  { capture, append } mode;
 
+/* tabella dei fattoriali di 1/n!, dove 0 <= n < 30 */
+static double ftable[]  = { 0.0, 1.0, 0.5, 0.166667, 0.0416667, 0.00833333, 0.00138889, 0.000198413, 
+						    2.48016e-05, 2.75573e-06, 2.75573e-07, 2.50521e-08, 2.08768e-09, 5.17584e-10, 
+						    7.81894e-10, 4.98925e-10, 4.98955e-10, -3.46594e-09, -1.11305e-09, 9.12062e-09, 
+						   -4.75707e-10, -8.3674e-10, -1.91309e-09, 1.15948e-09, -1.28875e-09, 4.81654e-10, 
+						   -5.39409e-10, 6.73499e-10, -7.26886e-10, -8.05468e-10 };
+/* intervallo in cui posizionare x */
+static double offset[]  = { 0.0, M_PI };
+/* sviluppo in serie di Taylor della funzione coseno 
+ * 
+ * x     : valore per cui calcolare il coseno .
+ * terms : numero di termini da usare nello sviluppo dove 0 <= terms < 30 e terms è un numero pari .
+ */
+inline double taylor_cosine( double x, int terms ) {
+	
+    int i        = terms,
+	    quadrant = x * TWO_O_M_PI; /* 0, 1, 2 o 3 */
+	double x2, r;
+	
+	/* tariamo x in modo tale che −π/2 < x < π/2 */
+    x         = x - quadrant * H_M_PI;
+    quadrant += 1;
+    x         = offset[ (quadrant >> 1) & 1 ] - x;
+    x2        = -(x*x);
+	/* eseguo lo sviluppo in serie */
+    r = ftable[i] * x2;
+    for( i -= 2; i > 0; i -= 2 ){
+    	r += ftable[i];
+        r *= x2;
+    }
+
+    return r + 1;
+}
+
 void helpandusage()  {
 	fprintf (stderr,
-			"---=== BlackLight's && evilsocket's vocal recognition v.0.1b ===---\n"
+			"---=== BlackLight's & evilsocket's vocal recognition v.0.1b ===---\n"
 			"author @ blacklight@autistici.org\n"
 			"author @ evilsocket@gmail.com\n\n"
 			"Usage: vocal [-d <device>] [-a] [-c <file>] [-h]\n\n"
@@ -105,7 +139,7 @@ int main (int argc, char **argv)  {
 
 		for (j=0; j<TOTSIZE; ++j)  {
 			if (t && j)
-				v += buf[j] * cos(t*j);
+				v += buf[j] * taylor_cosine( t * j, 10 );
 			else
 				v += buf[j];
 		}
@@ -161,16 +195,18 @@ int main (int argc, char **argv)  {
 
 					match[j-2]=0;
 					value = atof(match[0]);
+					
+					double delta = ABS(ABS(value)-ABS(sum));
 
-					if (ABS(ABS(value)-ABS(sum)) <= 0.025)  {
+					if ( delta <= 0.025 )  {
 						if (!recognized)  {
-							deviance = ABS(ABS(value)-ABS(sum));
-							cmd = strdup(tmp);
-							recognized=1;
+							deviance   = delta;
+							cmd        = strdup(tmp);
+							recognized = 1;
 						} else {
-							if (ABS(ABS(value)-ABS(sum)) < deviance)  {
-								deviance = ABS(ABS(value)-ABS(sum));
-								cmd = strdup(tmp);
+							if (delta < deviance)  {
+								deviance = delta;
+								cmd      = strdup(tmp);
 							}
 						}
 					}
diff --git a/vocal.h b/vocal.h
index 0d78beb..842f6fb 100644
--- a/vocal.h
+++ b/vocal.h
@@ -39,10 +39,14 @@
 #define	SAMPLE_SIZE	(int) (LENGTH*RATE*SIZE*CHANNELS/8)
 
 #ifndef	M_PI
-#define	M_PI		3.14159265358979323846
+#	define	M_PI		3.14159265358979323846
 #endif
-
+/* M_PI * 2 */
 #define D_M_PI  6.28318530717958623199592693708837032318115234375
+/* M_PI / 2 */
+#define H_M_PI  1.570796327
+/* 2 / M_PI */
+#define TWO_O_M_PI 0.636619772
 
 typedef unsigned char u8;
 typedef unsigned int u32;
@@ -50,9 +54,6 @@ typedef unsigned int u32;
 int init_dsp();
 char* getline (FILE *fp);
 char** preg_match (char *regex, char* s, int *size);
-double fourier (int u, u8* buf, int N);
 double ABS (double x);
-char *strdup (__const char *__s);
-int snprintf (char *__restrict __s, size_t __maxlen,
-		     __const char *__restrict __format, ...)
-     __THROW __attribute__ ((__format__ (__printf__, 3, 4)));
+
+