add numerical recipes library

lib/nr/k_and_r/recipes/sprspm.c

@@ -0,0 +1,47 @@
+
+void sprspm(sa,ija,sb,ijb,sc,ijc)
+float sa[],sb[],sc[];
+unsigned long ija[],ijb[],ijc[];
+{
+	void nrerror();
+	unsigned long i,ijma,ijmb,j,m,ma,mb,mbb,mn;
+	float sum;
+
+	if (ija[1] != ijb[1] || ija[1] != ijc[1])
+		nrerror("sprspm: sizes do not match");
+	for (i=1;i<=ijc[1]-2;i++) {
+		j=m=i;
+		mn=ijc[i];
+		sum=sa[i]*sb[i];
+		for (;;) {
+			mb=ijb[j];
+			for (ma=ija[i];ma<=ija[i+1]-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]-1;mbb++) {
+				if (ijb[mbb] == i) sum += sa[i]*sb[mbb];
+			}
+			sc[m]=sum;
+			sum=0.0;
+			if (mn >= ijc[i+1]) break;
+			j=ijc[m=mn++];
+		}
+	}
+}