 LAPACK  3.6.1 LAPACK: Linear Algebra PACKage
 double precision function dla_gerpvgrw ( integer N, integer NCOLS, double precision, dimension( lda, * ) A, integer LDA, double precision, dimension( ldaf, * ) AF, integer LDAF )

DLA_GERPVGRW

Purpose:
``` DLA_GERPVGRW computes the reciprocal pivot growth factor
norm(A)/norm(U). The "max absolute element" norm is used. If this is
much less than 1, the stability of the LU factorization of the
(equilibrated) matrix A could be poor. This also means that the
solution X, estimated condition numbers, and error bounds could be
unreliable.```
Parameters
 [in] N ``` N is INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0.``` [in] NCOLS ``` NCOLS is INTEGER The number of columns of the matrix A. NCOLS >= 0.``` [in] A ``` A is DOUBLE PRECISION array, dimension (LDA,N) On entry, the N-by-N matrix A.``` [in] LDA ``` LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).``` [in] AF ``` AF is DOUBLE PRECISION array, dimension (LDAF,N) The factors L and U from the factorization A = P*L*U as computed by DGETRF.``` [in] LDAF ``` LDAF is INTEGER The leading dimension of the array AF. LDAF >= max(1,N).```
Date
November 2011

Definition at line 102 of file dla_gerpvgrw.f.

102 *
103 * -- LAPACK computational routine (version 3.4.0) --
104 * -- LAPACK is a software package provided by Univ. of Tennessee, --
105 * -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
106 * November 2011
107 *
108 * .. Scalar Arguments ..
109  INTEGER n, ncols, lda, ldaf
110 * ..
111 * .. Array Arguments ..
112  DOUBLE PRECISION a( lda, * ), af( ldaf, * )
113 * ..
114 *
115 * =====================================================================
116 *
117 * .. Local Scalars ..
118  INTEGER i, j
119  DOUBLE PRECISION amax, umax, rpvgrw
120 * ..
121 * .. Intrinsic Functions ..
122  INTRINSIC abs, max, min
123 * ..
124 * .. Executable Statements ..
125 *
126  rpvgrw = 1.0d+0
127
128  DO j = 1, ncols
129  amax = 0.0d+0
130  umax = 0.0d+0
131  DO i = 1, n
132  amax = max( abs( a( i, j ) ), amax )
133  END DO
134  DO i = 1, j
135  umax = max( abs( af( i, j ) ), umax )
136  END DO
137  IF ( umax /= 0.0d+0 ) THEN
138  rpvgrw = min( amax / umax, rpvgrw )
139  END IF
140  END DO
141  dla_gerpvgrw = rpvgrw
double precision function dla_gerpvgrw(N, NCOLS, A, LDA, AF, LDAF)
DLA_GERPVGRW
Definition: dla_gerpvgrw.f:102

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