#include <math.h>#define SWAP(a,b) {dum=(a);(a)=(b);(b)=dum;}#define TINY 1.0e-20void bandec(float **a, unsigned long n, int m1, int m2, float **al,	unsigned long indx[], float *d){	unsigned long i,j,k,l;	int mm;	float dum;	mm=m1+m2+1;	l=m1;	for (i=1;i<=m1;i++) {		for (j=m1+2-i;j<=mm;j++) a[i][j-l]=a[i][j];		l--;		for (j=mm-l;j<=mm;j++) a[i][j]=0.0;	}	*d=1.0;	l=m1;	for (k=1;k<=n;k++) {		dum=a[k][1];		i=k;		if (l < n) l++;		for (j=k+1;j<=l;j++) {			if (fabs(a[j][1]) > fabs(dum)) {				dum=a[j][1];				i=j;			}		}		indx[k]=i;		if (dum == 0.0) a[k][1]=TINY;		if (i != k) {			*d = -(*d);			for (j=1;j<=mm;j++) SWAP(a[k][j],a[i][j])		}		for (i=k+1;i<=l;i++) {			dum=a[i][1]/a[k][1];			al[k][i-k]=dum;			for (j=2;j<=mm;j++) a[i][j-1]=a[i][j]-dum*a[k][j];			a[i][mm]=0.0;		}	}}#undef SWAP#undef TINY