Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?la_syrpvgrw
Computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric indefinite matrix.
Syntax
call sla_syrpvgrw ( uplo , n , info , a , lda , af , ldaf,ipiv , work )
call dla_syrpvgrw ( uplo , n , info , a , lda , af , ldaf,ipiv , work )
call cla_syrpvgrw ( uplo , n , info , a , lda , af , ldaf,ipiv , work )
call zla_syrpvgrw ( uplo , n , info , a , lda , af , ldaf,ipiv , work )
Include Files
mkl.fi
Description
The ?la_syrpvgrw routine 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.
Input Parameters
uplo
CHARACTER*1 . Must be ‘U’ or ‘L’ .
Specifies the triangle of A to store:
If uplo = 'U' , the upper triangle of A is stored,
If uplo = 'L' , the lower triangle of A is stored.
n
INTEGER . The number of linear equations, the order of the matrix A ; n ≥ 0.
info
INTEGER . The value of INFO returned from ?sytrf , that is, the pivot in column info is exactly 0.
a , af
REAL for sla_syrpvgrw
DOUBLE PRECISION for dla_syrpvgrw
COMPLEX for cla_syrpvgrw
DOUBLE COMPLEX for zla_syrpvgrw .
Arrays: a(lda,*) , af(ldaf,*) .
The array a contains the input n -by- n matrix A . The second dimension of a must be at least max(1,n) .
The array af contains the block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by ?sytrf .
lda
INTEGER . The leading dimension of a ; lda≥ max(1,n) .
ldaf
INTEGER . The leading dimension of af ; ldaf≥ max(1,n) .
ipiv
INTEGER .
Array, DIMENSION n . Details of the interchanges and the block structure of D as determined by ?sytrf .
work
REAL for sla_syrpvgrw and cla_syrpvgrw
DOUBLE PRECISION for dla_syrpvgrw and zla_syrpvgrw .
Workspace array, dimension 2* n .