compute bezout coefficients for 3 or more inputs

cmd/gcd.go

@@ -32,21 +32,32 @@ func gcd(cmd *cobra.Command, args []string) {
 	var z big.Int
 	var w big.Int
 
-	if extended && len(args) > 2 {
+	coeffs := make([]big.Int, len(args))
-		log.Fatal("--extended unsupported for more than two values")
-	}
 
-	for _, s := range args {
+	for i, s := range args {
 		_, ok := w.SetString(s, 10)
 		if !ok {
 			log.Fatal("invalid input " + s)
 		}
 
 		z.GCD(&x, &y, &z, &w)
+
+		for j, c := range coeffs {
+			if j == i {
+				coeffs[j].Set(&y)
+			} else {
+				coeffs[j].Mul(&c, &x)
+			}
+
+		}
 	}
 
 	if extended {
-		fmt.Println(&z, &x, &y)
+		fmt.Print(&z)
+		for _, c := range coeffs {
+			fmt.Printf(" %s", &c)
+		}
+		fmt.Println()
 	} else {
 		fmt.Println(&z)
 	}