add numerical recipes library

lib/nr/cpp/recipes/chsone.cpp

@@ -0,0 +1,18 @@
+#include "nr.h"
+
+void NR::chsone(Vec_I_DP &bins, Vec_I_DP &ebins, const int knstrn, DP &df,
+	DP &chsq, DP &prob)
+{
+	int j;
+	DP temp;
+
+	int nbins=bins.size();
+	df=nbins-knstrn;
+	chsq=0.0;
+	for (j=0;j<nbins;j++) {
+		if (ebins[j] <= 0.0) nrerror("Bad expected number in chsone");
+		temp=bins[j]-ebins[j];
+		chsq += temp*temp/ebins[j];
+	}
+	prob=gammq(0.5*df,0.5*chsq);
+}