#define SWAP(a,b) {dum=(a);(a)=(b);(b)=dum;}void banbks(float **a, unsigned long n, int m1, int m2, float **al,	unsigned long indx[], float b[]){	unsigned long i,k,l;	int mm;	float dum;	mm=m1+m2+1;	l=m1;	for (k=1;k<=n;k++) {		i=indx[k];		if (i != k) SWAP(b[k],b[i])		if (l < n) l++;		for (i=k+1;i<=l;i++) b[i] -= al[k][i-k]*b[k];	}	l=1;	for (i=n;i>=1;i--) {		dum=b[i];		for (k=2;k<=l;k++) dum -= a[i][k]*b[k+i-1];		b[i]=dum/a[i][1];		if (l < mm) l++;	}}#undef SWAP