add numerical recipes library

lib/nr/k_and_r/recipes/bksub.c

@@ -0,0 +1,25 @@
+
+void bksub(ne,nb,jf,k1,k2,c)
+float ***c;
+int jf,k1,k2,nb,ne;
+{
+	int nbf,im,kp,k,j,i;
+	float xx;
+
+	nbf=ne-nb;
+	im=1;
+	for (k=k2;k>=k1;k--) {
+		if (k == k1) im=nbf+1;
+		kp=k+1;
+		for (j=1;j<=nbf;j++) {
+			xx=c[j][jf][kp];
+			for (i=im;i<=ne;i++)
+				c[i][jf][k] -= c[i][j][k]*xx;
+		}
+	}
+	for (k=k1;k<=k2;k++) {
+		kp=k+1;
+		for (i=1;i<=nb;i++) c[i][1][k]=c[i+nbf][jf][k];
+		for (i=1;i<=nbf;i++) c[i+nb][1][k]=c[i][jf][kp];
+	}
+}