add numerical recipes library

lib/nr/cpp/recipes/sprstm.cpp

@@ -0,0 +1,50 @@
+#include <cmath>
+#include "nr.h"
+using namespace std;
+
+void NR::sprstm(Vec_I_DP &sa, Vec_I_INT &ija, Vec_I_DP &sb, Vec_I_INT &ijb,
+	const DP thresh, Vec_O_DP &sc, Vec_O_INT &ijc)
+{
+	int i,ijma,ijmb,j,k,ma,mb,mbb;
+	DP sum;
+
+	if (ija[0] != ijb[0]) nrerror("sprstm: sizes do not match");
+	int nmax=sc.size();
+	ijc[0]=k=ija[0];
+	for (i=0;i<ija[0]-1;i++) {
+		for (j=0;j<ijb[0]-1;j++) {
+			if (i == j) sum=sa[i]*sb[j]; else sum=0.0e0;
+			mb=ijb[j];
+			for (ma=ija[i];ma<ija[i+1];ma++) {
+				ijma=ija[ma];
+				if (ijma == j) sum += sa[ma]*sb[j];
+				else {
+					while (mb < ijb[j+1]) {
+						ijmb=ijb[mb];
+						if (ijmb == i) {
+							sum += sa[i]*sb[mb++];
+							continue;
+						} else if (ijmb < ijma) {
+							mb++;
+							continue;
+						} else if (ijmb == ijma) {
+							sum += sa[ma]*sb[mb++];
+							continue;
+						}
+						break;
+					}
+				}
+			}
+			for (mbb=mb;mbb<ijb[j+1];mbb++) {
+				if (ijb[mbb] == i) sum += sa[i]*sb[mbb];
+			}
+			if (i == j) sc[i]=sum;
+			else if (fabs(sum) > thresh) {
+				if (k > nmax-1) nrerror("sprstm: sc and ijc too small");
+				sc[k]=sum;
+				ijc[k++]=j;
+			}
+		}
+		ijc[i+1]=k;
+	}
+}