add numerical recipes library

lib/nr/cpp/recipes/arcsum.cpp

@@ -0,0 +1,19 @@
+#include "nr.h"
+
+void NR::arcsum(Vec_I_ULNG &iin, Vec_O_ULNG &iout, unsigned long ja,
+	const int nwk, const unsigned long nrad, const unsigned long nc)
+{
+	int karry=0;
+	unsigned long j,jtmp;
+
+	for (j=nwk-1;j>nc;j--) {
+		jtmp=ja;
+		ja /= nrad;
+		iout[j]=iin[j]+(jtmp-ja*nrad)+karry;
+		if (iout[j] >= nrad) {
+			iout[j] -= nrad;
+			karry=1;
+		} else karry=0;
+	}
+	iout[nc]=iin[nc]+ja+karry;
+}