Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?la_porpvgrw
Computes the reciprocal pivot growth factor norm(A)/norm(U) for a symmetric or Hermitian positive-definite matrix.
Syntax
call sla_porpvgrw ( uplo , ncols , a , lda , af , ldaf , work )
call dla_porpvgrw ( uplo , ncols , a , lda , af , ldaf , work )
call cla_porpvgrw ( uplo , ncols , a , lda , af , ldaf , work )
call zla_porpvgrw ( uplo , ncols , a , lda , af , ldaf , work )
Include Files
mkl.fi
Description
The ?la_porpvgrw 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.
ncols
INTEGER . The number of columns of the matrix A ; ncols ≥ 0.
a , af
REAL for sla_porpvgrw
DOUBLE PRECISION for dla_porpvgrw
COMPLEX for cla_porpvgrw
DOUBLE COMPLEX for zla_porpvgrw .
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 triangular factor L or U from the Cholesky factorization as computed by ?potrf :
A = U^{T}*U or A = L*L^{T} for real flavors,
A = U^{H}*U or A = L*L^{H} for complex flavors.
lda
INTEGER . The leading dimension of a ; lda≥ max(1,n) .
ldaf
INTEGER . The leading dimension of af ; ldaf≥ max(1,n) .
work
REAL for sla_porpvgrw and cla_porpvgrw
DOUBLE PRECISION for dla_porpvgrw and zla_porpvgrw .
Workspace array, dimension 2* n .