# dspmv(3) [centos man page]

```dspmv.f(3)							      LAPACK								dspmv.f(3)

NAME
dspmv.f -

SYNOPSIS
Functions/Subroutines
subroutine dspmv (UPLO, N, ALPHA, AP, X, INCX, BETA, Y, INCY)
DSPMV

Function/Subroutine Documentation
subroutine dspmv (characterUPLO, integerN, double precisionALPHA, double precision, dimension(*)AP, double precision, dimension(*)X,
integerINCX, double precisionBETA, double precision, dimension(*)Y, integerINCY)
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 of 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 of 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 of 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.

Date:
November 2011

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 148 of file dspmv.f.

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

Version 3.4.2							  Tue Sep 25 2012							dspmv.f(3)```

## Check Out this Related Man Page

```DSPMV(3)							   BLAS routine 							  DSPMV(3)

NAME
DSPMV - perform the matrix-vector operation   y := alpha*A*x + beta*y,

SYNOPSIS
SUBROUTINE DSPMV ( UPLO, N, ALPHA, AP, X, INCX, BETA, Y, INCY )

DOUBLE	PRECISION ALPHA, BETA

INTEGER	INCX, INCY, N

CHARACTER*1	UPLO

DOUBLE	PRECISION AP( * ), X( * ), Y( * )

PURPOSE
DSPMV  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.

PARAMETERS
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  - DOUBLE PRECISION.
On entry, ALPHA specifies the scalar alpha.  Unchanged on exit.

AP     - DOUBLE PRECISION array of 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 symmet-
ric 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.  Unchanged on exit.

X      - DOUBLE PRECISION array of 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   - INTEGER.
On entry, INCX specifies the increment for the elements of X. INCX must not be zero.  Unchanged on exit.

BETA   - 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      - DOUBLE PRECISION array of 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 elements of Y. INCY must not be zero.  Unchanged on exit.

Level 2 Blas routine.

-- Written on 22-October-1986.  Jack Dongarra, Argonne National Lab.  Jeremy Du Croz, Nag Central Office.  Sven Hammarling, Nag Cen-
tral Office.  Richard Hanson, Sandia National Labs.

BLAS routine							  16 October 1992							  DSPMV(3)```
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