add numerical recipes library

lib/nr/k_and_r/recipes/tutest.c

@@ -0,0 +1,18 @@
+
+#include <math.h>
+#include "nrutil.h"
+
+void tutest(data1,n1,data2,n2,t,prob)
+float *prob,*t,data1[],data2[];
+unsigned long n1,n2;
+{
+	float betai();
+	void avevar();
+	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)));
+}