SRC/zlaqsy.f(3)

NAME
SRC/zlaqsy.f

SYNOPSIS

  Functions/Subroutines
subroutine zlaqsy (uplo, n, a, lda, s, scond, amax, equed)
ZLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ.

Function/Subroutine Documentation

  subroutine zlaqsy (character uplo, integer n, complex*16, dimension( lda, * ) a, integer lda, double precision, dimension( * ) s, double precision scond, double precision amax, character equed)

ZLAQSY scales a symmetric/Hermitian matrix, using scaling factors computed by spoequ.

Purpose:

    !>
    !> ZLAQSY equilibrates a symmetric matrix A using the scaling factors
    !> in the vector S.
    !>

Parameters
    UPLO

    !>          UPLO is CHARACTER*1
    !>          Specifies whether the upper or lower triangular part of the
    !>          symmetric matrix A is stored.
    !>          = 'U':  Upper triangular
    !>          = 'L':  Lower triangular
    !>

    N

    !>          N is INTEGER
    !>          The order of the matrix A.  N >= 0.
    !>

    A

    !>          A is COMPLEX*16 array, dimension (LDA,N)
    !>          On entry, the symmetric matrix A.  If UPLO = 'U', the leading
    !>          n by n upper triangular part of A contains the upper
    !>          triangular part of the matrix A, and the strictly lower
    !>          triangular part of A is not referenced.  If UPLO = 'L', the
    !>          leading n by n lower triangular part of A contains the lower
    !>          triangular part of the matrix A, and the strictly upper
    !>          triangular part of A is not referenced.
    !>
    !>          On exit, if EQUED = 'Y', the equilibrated matrix:
    !>          diag(S) * A * diag(S).
    !>

    LDA

    !>          LDA is INTEGER
    !>          The leading dimension of the array A.  LDA >= max(N,1).
    !>

    S

    !>          S is DOUBLE PRECISION array, dimension (N)
    !>          The scale factors for A.
    !>

    SCOND

    !>          SCOND is DOUBLE PRECISION
    !>          Ratio of the smallest S(i) to the largest S(i).
    !>

    AMAX

    !>          AMAX is DOUBLE PRECISION
    !>          Absolute value of largest matrix entry.
    !>

    EQUED

    !>          EQUED is CHARACTER*1
    !>          Specifies whether or not equilibration was done.
    !>          = 'N':  No equilibration.
    !>          = 'Y':  Equilibration was done, i.e., A has been replaced by
    !>                  diag(S) * A * diag(S).
    !>

Internal Parameters:

    !>  THRESH is a threshold value used to decide if scaling should be done
    !>  based on the ratio of the scaling factors.  If SCOND < THRESH,
    !>  scaling is done.
    !>
    !>  LARGE and SMALL are threshold values used to decide if scaling should
    !>  be done based on the absolute size of the largest matrix element.
    !>  If AMAX > LARGE or AMAX < SMALL, scaling is done.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 133 of file zlaqsy.f.

Author

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