add numerical recipes library

lib/nr/ansi/recipes/tutest.c

@@ -0,0 +1,19 @@
+
+#include <math.h>
+#define NRANSI
+#include "nrutil.h"
+
+void tutest(float data1[], unsigned long n1, float data2[], unsigned long n2,
+	float *t, float *prob)
+{
+	void avevar(float data[], unsigned long n, float *ave, float *var);
+	float betai(float a, float b, float x);
+	float var1,var2,df,ave1,ave2;
+
+	avevar(data1,n1,&ave1,&var1);
+	avevar(data2,n2,&ave2,&var2);
+	*t=(ave1-ave2)/sqrt(var1/n1+var2/n2);
+	df=SQR(var1/n1+var2/n2)/(SQR(var1/n1)/(n1-1)+SQR(var2/n2)/(n2-1));
+	*prob=betai(0.5*df,0.5,df/(df+SQR(*t)));
+}
+#undef NRANSI