#define NRANSI#include "nrutil.h"#define SWAP(a,b) itemp=(a);(a)=(b);(b)=itemp;#define M 7#define NSTACK 50void indexx(unsigned long n, float arr[], unsigned long indx[]){	unsigned long i,indxt,ir=n,itemp,j,k,l=1;	int jstack=0,*istack;	float 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 indexx.");			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