1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
|
// CSparse/Source/cs_norm: 1-norm of a sparse matrix
// CSparse, Copyright (c) 2006-2022, Timothy A. Davis. All Rights Reserved.
// SPDX-License-Identifier: LGPL-2.1+
#include "cs.h"
/* 1-norm of a sparse matrix = max (sum (abs (A))), largest column sum */
double cs_norm (const cs *A)
{
csi p, j, n, *Ap ;
double *Ax, norm = 0, s ;
if (!CS_CSC (A) || !A->x) return (-1) ; /* check inputs */
n = A->n ; Ap = A->p ; Ax = A->x ;
for (j = 0 ; j < n ; j++)
{
for (s = 0, p = Ap [j] ; p < Ap [j+1] ; p++) s += fabs (Ax [p]) ;
norm = CS_MAX (norm, s) ;
}
return (norm) ;
}
|
