add numerical recipes library

lib/nr/ansi/recipes/iindexx.c

@@ -0,0 +1,72 @@
+
+#define NRANSI
+#include "nrutil.h"
+#define SWAP(a,b) itemp=(a);(a)=(b);(b)=itemp;
+#define M 7
+#define NSTACK 50
+
+void iindexx(unsigned long n, long arr[], unsigned long indx[])
+{
+	unsigned long i,indxt,ir=n,itemp,j,k,l=1;
+	int jstack=0,*istack;
+	long a;
+
+	istack=ivector(1,NSTACK);
+	for (j=1;j<=n;j++) indx[j]=j;
+	for (;;) {
+		if (ir-l < M) {
+			for (j=l+1;j<=ir;j++) {
+				indxt=indx[j];
+				a=arr[indxt];
+				for (i=j-1;i>=l;i--) {
+					if (arr[indx[i]] <= a) break;
+					indx[i+1]=indx[i];
+				}
+				indx[i+1]=indxt;
+			}
+			if (jstack == 0) break;
+			ir=istack[jstack--];
+			l=istack[jstack--];
+		} else {
+			k=(l+ir) >> 1;
+			SWAP(indx[k],indx[l+1]);
+			if (arr[indx[l]] > arr[indx[ir]]) {
+				SWAP(indx[l],indx[ir])
+			}
+			if (arr[indx[l+1]] > arr[indx[ir]]) {
+				SWAP(indx[l+1],indx[ir])
+			}
+			if (arr[indx[l]] > arr[indx[l+1]]) {
+				SWAP(indx[l],indx[l+1])
+			}
+			i=l+1;
+			j=ir;
+			indxt=indx[l+1];
+			a=arr[indxt];
+			for (;;) {
+				do i++; while (arr[indx[i]] < a);
+				do j--; while (arr[indx[j]] > a);
+				if (j < i) break;
+				SWAP(indx[i],indx[j])
+			}
+			indx[l+1]=indx[j];
+			indx[j]=indxt;
+			jstack += 2;
+			if (jstack > NSTACK) nrerror("NSTACK too small in iindexx.");
+			if (ir-i+1 >= j-l) {
+				istack[jstack]=ir;
+				istack[jstack-1]=i;
+				ir=j-1;
+			} else {
+				istack[jstack]=j-1;
+				istack[jstack-1]=l;
+				l=i;
+			}
+		}
+	}
+	free_ivector(istack,1,NSTACK);
+}
+#undef M
+#undef NSTACK
+#undef SWAP
+#undef NRANSI