add numerical recipes library

lib/nr/cpp/recipes/tutest.cpp

@@ -0,0 +1,16 @@
+#include <cmath>
+#include "nr.h"
+using namespace std;
+
+void NR::tutest(Vec_I_DP &data1, Vec_I_DP &data2, DP &t, DP &prob)
+{
+	DP var1,var2,df,ave1,ave2;
+
+	int n1=data1.size();
+	int n2=data2.size();
+	avevar(data1,ave1,var1);
+	avevar(data2,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)));
+}