BLAS/SRC/dspmv.f(3)        Library Functions Manual        BLAS/SRC/dspmv.f(3)

NAME
       BLAS/SRC/dspmv.f

SYNOPSIS
   Functions/Subroutines
       subroutine dspmv (uplo, n, alpha, ap, x, incx, beta, y, incy)
           DSPMV

Function/Subroutine Documentation
   subroutine dspmv (character uplo, integer n, double precision alpha, double
       precision, dimension(*) ap, double precision, dimension(*) x, integer
       incx, double precision beta, double precision, dimension(*) y, integer
       incy)
       DSPMV

       Purpose:


            DSPMV  performs the matrix-vector operation

               y := alpha*A*x + beta*y,

            where alpha and beta are scalars, x and y are n element vectors and
            A is an n by n symmetric matrix, supplied in packed form.

       Parameters
           UPLO

                     UPLO is CHARACTER*1
                      On entry, UPLO specifies whether the upper or lower
                      triangular part of the matrix A is supplied in the packed
                      array AP as follows:

                         UPLO = 'U' or 'u'   The upper triangular part of A is
                                             supplied in AP.

                         UPLO = 'L' or 'l'   The lower triangular part of A is
                                             supplied in AP.

           N

                     N is INTEGER
                      On entry, N specifies the order of the matrix A.
                      N must be at least zero.

           ALPHA

                     ALPHA is DOUBLE PRECISION.
                      On entry, ALPHA specifies the scalar alpha.

           AP

                     AP is DOUBLE PRECISION array, dimension at least
                      ( ( n*( n + 1 ) )/2 ).
                      Before entry with UPLO = 'U' or 'u', the array AP must
                      contain the upper triangular part of the symmetric matrix
                      packed sequentially, column by column, so that AP( 1 )
                      contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 )
                      and a( 2, 2 ) respectively, and so on.
                      Before entry with UPLO = 'L' or 'l', the array AP must
                      contain the lower triangular part of the symmetric matrix
                      packed sequentially, column by column, so that AP( 1 )
                      contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 )
                      and a( 3, 1 ) respectively, and so on.

           X

                     X is DOUBLE PRECISION array, dimension at least
                      ( 1 + ( n - 1 )*abs( INCX ) ).
                      Before entry, the incremented array X must contain the n
                      element vector x.

           INCX

                     INCX is INTEGER
                      On entry, INCX specifies the increment for the elements of
                      X. INCX must not be zero.

           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.

           Y

                     Y is DOUBLE PRECISION array, dimension at least
                      ( 1 + ( n - 1 )*abs( INCY ) ).
                      Before entry, the incremented array Y must contain the n
                      element 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.

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Further Details:


             Level 2 Blas routine.
             The vector and matrix arguments are not referenced when N = 0, or M = 0

             -- 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.

       Definition at line 146 of file dspmv.f.

Author
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LAPACK                          Version 3.12.0             BLAS/SRC/dspmv.f(3)