void bksub(int ne, int nb, int jf, int k1, int k2, float ***c){	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];	}}