LA_HERPVGRW - 5.2 English - 68552

AOCL API Guide (68552)

Document ID
68552
Release Date
2025-12-29
Version
5.2 English
template<typename T, typename Ta>
Ta la_herpvgrw(char *uplo, integer *n, integer *info, T *a, integer *lda, T *af, integer *ldaf, integer *ipiv, Ta *work)#

LA_HERPVGRW computes the reciprocal pivot growth factor norm(A)/norm(U)

Purpose:

 LA_HERPVGRW 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:
  • UPLO[in]

    UPLO is CHARACTER*1

    = ‘U’: Upper triangle of A is stored;

    = ‘L’: Lower triangle of A is stored.
  • N[in]

    N is INTEGER

    The number of linear equations, i.e., the order of the matrix A. N >= 0.

  • INFO[in]

    INFO is INTEGER

    The value of INFO returned from SSYTRF, .i.e., the pivot in column INFO is exactly 0.

  • A[in]

    A is COMPLEX array, dimension (LDA,N)

    On entry, the N-by-N matrix A.

  • LDA[in]

    LDA is INTEGER

    The leading dimension of the array A. LDA >= fla_max(1,N).

  • AF[in]

    AF is COMPLEX array, dimension (LDAF,N)

    The block diagonal matrix D and the multipliers used to obtain the factor U or L as computed by CHETRF.

  • LDAF[in]

    LDAF is INTEGER

    The leading dimension of the array AF. LDAF >= fla_max(1,N).

  • IPIV[in]

    IPIV is INTEGER array, dimension (N)

    Details of the interchanges and the block structure of D as determined by CHETRF.

  • WORK[out] WORK is REAL array, dimension (2*N)