sla_syrpvgrw (3) - Linux Man Pages
REAL function sla_syrpvgrw (character*1UPLO, integerN, integerINFO, real, dimension( lda, * )A, integerLDA, real, dimension( ldaf, * )AF, integerLDAF, integer, dimension( * )IPIV, real, dimension( * )WORK)
SLA_SYRPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.
SLA_SYRPVGRW 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.
UPLO is CHARACTER*1 = 'U': Upper triangle of A is stored; = 'L': Lower triangle of A is stored.
N is INTEGER The number of linear equations, i.e., the order of the matrix A. N >= 0.
INFO is INTEGER The value of INFO returned from SSYTRF, .i.e., the pivot in column INFO is exactly 0.
A is REAL array, dimension (LDA,N) On entry, the N-by-N matrix A.
LDA is INTEGER The leading dimension of the array A. LDA >= max(1,N).
AF is REAL array, dimension (LDAF,N) The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by SSYTRF.
LDAF is INTEGER The leading dimension of the array AF. LDAF >= max(1,N).
IPIV is INTEGER array, dimension (N) Details of the interchanges and the block structure of D as determined by SSYTRF.
WORK is REAL array, dimension (2*N)
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
- September 2012
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