add numerical recipes library

lib/nr/k_and_r/recipes/quadct.c

@@ -0,0 +1,21 @@
+
+void quadct(x,y,xx,yy,nn,fa,fb,fc,fd)
+float *fa,*fb,*fc,*fd,x,xx[],y,yy[];
+unsigned long nn;
+{
+	unsigned long k,na,nb,nc,nd;
+	float ff;
+	na=nb=nc=nd=0;
+	for (k=1;k<=nn;k++) {
+		if (yy[k] > y) {
+			xx[k] > x ? ++na : ++nb;
+		} else {
+			xx[k] > x ? ++nd : ++nc;
+		}
+	}
+	ff=1.0/nn;
+	*fa=ff*na;
+	*fb=ff*nb;
+	*fc=ff*nc;
+	*fd=ff*nd;
+}