CSPMV(1) LAPACK auxiliary routine (version 3.2) CSPMV(1)NAME
CSPMV - performs the matrix-vector operation y := alpha*A*x + beta*y,
SYNOPSIS
SUBROUTINE CSPMV( UPLO, N, ALPHA, AP, X, INCX, BETA, Y, INCY )
CHARACTER UPLO
INTEGER INCX, INCY, N
COMPLEX ALPHA, BETA
COMPLEX AP( * ), X( * ), Y( * )
PURPOSE
CSPMV performs the matrix-vector operation 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.
ARGUMENTS
UPLO (input) 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. Unchanged on exit.
N (input) INTEGER
On entry, N specifies the order of the matrix A. N must be at
least zero. Unchanged on exit.
ALPHA (input) COMPLEX
On entry, ALPHA specifies the scalar alpha. Unchanged on
exit.
AP (input) COMPLEX 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 sequen‐
tially, column by column, so that AP( 1 ) contains a( 1, 1 ),
AP( 2 ) and AP( 3 ) contain a( 2, 1 ) and a( 3, 1 ) respec‐
tively, and so on. Unchanged on exit.
X (input) COMPLEX array, dimension at least
( 1 + ( N - 1 )*abs( INCX ) ). Before entry, the incremented
array X must contain the N- element vector x. Unchanged on
exit.
INCX (input) INTEGER
On entry, INCX specifies the increment for the elements of X.
INCX must not be zero. Unchanged on exit.
BETA (input) COMPLEX
On entry, BETA specifies the scalar beta. When BETA is sup‐
plied as zero then Y need not be set on input. Unchanged on
exit.
Y (input/output) COMPLEX 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 (input) INTEGER
On entry, INCY specifies the increment for the elements of Y.
INCY must not be zero. Unchanged on exit.
LAPACK auxiliary routine (versioNovember 2008 CSPMV(1)
