SRC/zla_heamv.f(3)         Library Functions Manual         SRC/zla_heamv.f(3)

NAME
       SRC/zla_heamv.f

SYNOPSIS
   Functions/Subroutines
       subroutine zla_heamv (uplo, n, alpha, a, lda, x, incx, beta, y, incy)
           ZLA_HEAMV computes a matrix-vector product using a Hermitian
           indefinite matrix to calculate error bounds.

Function/Subroutine Documentation
   subroutine zla_heamv (integer uplo, integer n, double precision alpha,
       complex*16, dimension( lda, * ) a, integer lda, complex*16, dimension(
       * ) x, integer incx, double precision beta, double precision,
       dimension( * ) y, integer incy)
       ZLA_HEAMV computes a matrix-vector product using a Hermitian indefinite
       matrix to calculate error bounds.

       Purpose:


           !>
           !> ZLA_SYAMV  performs the matrix-vector operation
           !>
           !>         y := alpha*abs(A)*abs(x) + beta*abs(y),
           !>
           !> where alpha and beta are scalars, x and y are vectors and A is an
           !> n by n symmetric matrix.
           !>
           !> This function is primarily used in calculating error bounds.
           !> To protect against underflow during evaluation, components in
           !> the resulting vector are perturbed away from zero by (N+1)
           !> times the underflow threshold.  To prevent unnecessarily large
           !> errors for block-structure embedded in general matrices,
           !>  zero components are not perturbed.  A zero
           !> entry is considered  if all multiplications involved
           !> in computing that entry have at least one zero multiplicand.
           !>

       Parameters
           UPLO

           !>          UPLO is INTEGER
           !>           On entry, UPLO specifies whether the upper or lower
           !>           triangular part of the array A is to be referenced as
           !>           follows:
           !>
           !>              UPLO = BLAS_UPPER   Only the upper triangular part of A
           !>                                  is to be referenced.
           !>
           !>              UPLO = BLAS_LOWER   Only the lower triangular part of A
           !>                                  is to be referenced.
           !>
           !>           Unchanged on exit.
           !>

           N

           !>          N is INTEGER
           !>           On entry, N specifies the number of columns of the matrix A.
           !>           N must be at least zero.
           !>           Unchanged on exit.
           !>

           ALPHA

           !>          ALPHA is DOUBLE PRECISION .
           !>           On entry, ALPHA specifies the scalar alpha.
           !>           Unchanged on exit.
           !>

           A

           !>          A is COMPLEX*16 array, dimension ( LDA, n ).
           !>           Before entry, the leading m by n part of the array A must
           !>           contain the matrix of coefficients.
           !>           Unchanged on exit.
           !>

           LDA

           !>          LDA is INTEGER
           !>           On entry, LDA specifies the first dimension of A as declared
           !>           in the calling (sub) program. LDA must be at least
           !>           max( 1, n ).
           !>           Unchanged on exit.
           !>

           X

           !>          X is COMPLEX*16 array, dimension at least
           !>           ( 1 + ( n - 1 )*abs( INCX ) )
           !>           Before entry, the incremented array X must contain the
           !>           vector x.
           !>           Unchanged on exit.
           !>

           INCX

           !>          INCX is INTEGER
           !>           On entry, INCX specifies the increment for the elements of
           !>           X. INCX must not be zero.
           !>           Unchanged on exit.
           !>

           BETA

           !>          BETA is DOUBLE PRECISION .
           !>           On entry, BETA specifies the scalar beta. When BETA is
           !>           supplied as zero then Y need not be set on input.
           !>           Unchanged on exit.
           !>

           Y

           !>          Y is DOUBLE PRECISION array, dimension
           !>           ( 1 + ( n - 1 )*abs( INCY ) )
           !>           Before entry with BETA non-zero, the incremented array Y
           !>           must contain the vector y. On exit, Y is overwritten by the
           !>           updated vector y.
           !>

           INCY

           !>          INCY is INTEGER
           !>           On entry, INCY specifies the increment for the elements of
           !>           Y. INCY must not be zero.
           !>           Unchanged on exit.
           !>

       Author
           Univ. of Tennessee


           Univ. of California Berkeley


           Univ. of Colorado Denver


           NAG Ltd.

       Further Details:


           !>
           !>  Level 2 Blas routine.
           !>
           !>  -- Written on 22-October-1986.
           !>     Jack Dongarra, Argonne National Lab.
           !>     Jeremy Du Croz, Nag Central Office.
           !>     Sven Hammarling, Nag Central Office.
           !>     Richard Hanson, Sandia National Labs.
           !>  -- Modified for the absolute-value product, April 2006
           !>     Jason Riedy, UC Berkeley
           !>

       Definition at line 176 of file zla_heamv.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0              SRC/zla_heamv.f(3)