// CSparse/Source/cs_ltsolve: x=L'\b, back substitution where x and b are dense
// CSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
// SPDX-License-Identifier: LGPL-2.1+
#include "cs.h"
/* solve L'x=b where x and b are dense.  x=b on input, solution on output. */
csi cs_ltsolve (const cs *L, double *x)
{
    csi p, j, n, *Lp, *Li ;
    double *Lx ;
    if (!CS_CSC (L) || !x) return (0) ;                     /* check inputs */
    n = L->n ; Lp = L->p ; Li = L->i ; Lx = L->x ;
    for (j = n-1 ; j >= 0 ; j--)
    {
        for (p = Lp [j]+1 ; p < Lp [j+1] ; p++)
        {
            x [j] -= Lx [p] * x [Li [p]] ;
        }
        x [j] /= Lx [Lp [j]] ;
    }
    return (1) ;
}