Note: this is a BLAS routine and is not in libslatec.a
*DECK SSPMV
SUBROUTINE SSPMV (UPLO, N, ALPHA, AP, X, INCX, BETA, Y, INCY)
C***BEGIN PROLOGUE SSPMV
C***PURPOSE Perform the matrix-vector operation.
C***LIBRARY SLATEC (BLAS)
C***CATEGORY D1B4
C***TYPE SINGLE PRECISION (SSPMV-S, DSPMV-D, CSPMV-C)
C***KEYWORDS LEVEL 2 BLAS, LINEAR ALGEBRA
C***AUTHOR Dongarra, J. J., (ANL)
C Du Croz, J., (NAG)
C Hammarling, S., (NAG)
C Hanson, R. J., (SNLA)
C***DESCRIPTION
C
C SSPMV performs the matrix-vector operation
C
C y := alpha*A*x + beta*y,
C
C where alpha and beta are scalars, x and y are n element vectors and
C A is an n by n symmetric matrix, supplied in packed form.
C
C Parameters
C ==========
C
C UPLO - CHARACTER*1.
C On entry, UPLO specifies whether the upper or lower
C triangular part of the matrix A is supplied in the packed
C array AP as follows:
C
C UPLO = 'U' or 'u' The upper triangular part of A is
C supplied in AP.
C
C UPLO = 'L' or 'l' The lower triangular part of A is
C supplied in AP.
C
C Unchanged on exit.
C
C N - INTEGER.
C On entry, N specifies the order of the matrix A.
C N must be at least zero.
C Unchanged on exit.
C
C ALPHA - REAL .
C On entry, ALPHA specifies the scalar alpha.
C Unchanged on exit.
C
C AP - REAL array of DIMENSION at least
C ( ( n*( n + 1))/2).
C Before entry with UPLO = 'U' or 'u', the array AP must
C contain the upper triangular part of the symmetric matrix
C packed sequentially, column by column, so that AP( 1 )
C contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 1, 2 )
C and a( 2, 2 ) respectively, and so on.
C Before entry with UPLO = 'L' or 'l', the array AP must
C contain the lower triangular part of the symmetric matrix
C packed sequentially, column by column, so that AP( 1 )
C contains a( 1, 1 ), AP( 2 ) and AP( 3 ) contain a( 2, 1 )
C and a( 3, 1 ) respectively, and so on.
C Unchanged on exit.
C
C X - REAL array of dimension at least
C ( 1 + ( n - 1 )*abs( INCX ) ).
C Before entry, the incremented array X must contain the n
C element vector x.
C Unchanged on exit.
C
C INCX - INTEGER.
C On entry, INCX specifies the increment for the elements of
C X. INCX must not be zero.
C Unchanged on exit.
C
C BETA - REAL .
C On entry, BETA specifies the scalar beta. When BETA is
C supplied as zero then Y need not be set on input.
C Unchanged on exit.
C
C Y - REAL array of dimension at least
C ( 1 + ( n - 1 )*abs( INCY ) ).
C Before entry, the incremented array Y must contain the n
C element vector y. On exit, Y is overwritten by the updated
C vector y.
C
C INCY - INTEGER.
C On entry, INCY specifies the increment for the elements of
C Y. INCY must not be zero.
C Unchanged on exit.
C
C***REFERENCES Dongarra, J. J., Du Croz, J., Hammarling, S., and
C Hanson, R. J. An extended set of Fortran basic linear
C algebra subprograms. ACM TOMS, Vol. 14, No. 1,
C pp. 1-17, March 1988.
C***ROUTINES CALLED LSAME, XERBLA
C***REVISION HISTORY (YYMMDD)
C 861022 DATE WRITTEN
C 910605 Modified to meet SLATEC prologue standards. Only comment
C lines were modified. (BKS)
C***END PROLOGUE SSPMV