16 lines
436 B
C
16 lines
436 B
C
#include "cs.h"
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/* 1-norm of a sparse matrix = max (sum (abs (A))), largest column sum */
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double cs_norm (const cs *A)
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{
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int p, j, n, *Ap ;
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double *Ax, norm = 0, s ;
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if (!CS_CSC (A) || !A->x) return (-1) ; /* check inputs */
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n = A->n ; Ap = A->p ; Ax = A->x ;
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for (j = 0 ; j < n ; j++)
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{
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for (s = 0, p = Ap [j] ; p < Ap [j+1] ; p++) s += fabs (Ax [p]) ;
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norm = CS_MAX (norm, s) ;
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}
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return (norm) ;
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}
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