void bksub(int ne, int nb, int jf, int k1, int k2,
		   double c[], int nci, int ncj, int nck)
{
    int k,j,i,kp,nbf = ne - nb;
	double xx;
    for (k = k2; k>=k1; k--)
	{
        kp = k + 1;
        for (j = 1; j<=nbf; j++)
		{
            xx = c[((j-1)*ncj+jf-1)*nck+kp];
            for (i = 1; i<=ne; i++)
			{
                c[((i - 1) * ncj + jf - 1) * nck + k] = c[((i-1)
				  * ncj+jf-1)*nck+k]-c[((i-1)*ncj+j-1)*nck+k]*xx;
            }
        }
    }
    for (k = k1; k<=k2; k++)
	{
        kp = k + 1;
        for (i = 1; i<=nb; i++)
		{
            c[(i-1)*ncj*nck+k] = c[((i + nbf-1)*ncj+jf-1)*nck+k];
		}
        for (i = 1; i<=nbf; i++)
		{
            c[(i + nb-1)*ncj*nck+k] = c[((i-1)*ncj+jf-1)*nck+kp];
        }
    }
}