add numerical recipes library

lib/nr/ansi/recipes/evlmem.c

@@ -0,0 +1,20 @@
+
+#include <math.h>
+
+float evlmem(float fdt, float d[], int m, float xms)
+{
+	int i;
+	float sumr=1.0,sumi=0.0;
+	double wr=1.0,wi=0.0,wpr,wpi,wtemp,theta;
+
+	theta=6.28318530717959*fdt;
+	wpr=cos(theta);
+	wpi=sin(theta);
+	for (i=1;i<=m;i++) {
+		wr=(wtemp=wr)*wpr-wi*wpi;
+		wi=wi*wpr+wtemp*wpi;
+		sumr -= d[i]*wr;
+		sumi -= d[i]*wi;
+	}
+	return xms/(sumr*sumr+sumi*sumi);
+}