add numerical recipes library

lib/nr/k_and_r/recipes/piksrt.c

@@ -0,0 +1,18 @@
+
+void piksrt(n,arr)
+float arr[];
+int n;
+{
+	int i,j;
+	float a;
+
+	for (j=2;j<=n;j++) {
+		a=arr[j];
+		i=j-1;
+		while (i > 0 && arr[i] > a) {
+			arr[i+1]=arr[i];
+			i--;
+		}
+		arr[i+1]=a;
+	}
+}