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NAME CSPMV - perform 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 vec- tors and A is an n by n symmetric matrix, supplied in packed form. ARGUMENTS UPLO - 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 - INTEGER On entry, N specifies the order of the matrix A. N must be at least zero. Unchanged on exit. ALPHA - COMPLEX On entry, ALPHA specifies the scalar alpha. Unchanged on exit. AP - COMPLEX array, dimension at least ( ( N*( N + 1 ) )/2 ). Before entry with UPLO = 'U' or 'u', the array AP must contain the upper triangu- lar 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 tri- angular 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 ) respectively, and so on. Unchanged on exit. X - COMPLEX array, dimension at least ( 1 + ( N - 1 )*abs( INCX ) ). Before entry, the incremented array X must contain the N- element vec- tor x. Unchanged on exit. INCX - INTEGER On entry, INCX specifies the increment for the ele- ments of X. INCX must not be zero. Unchanged on exit. BETA - COMPLEX 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 - 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 - INTEGER On entry, INCY specifies the increment for the ele- ments of Y. INCY must not be zero. Unchanged on exit.