# dsymv.f(3) [centos man page]

```dsymv.f(3)							      LAPACK								dsymv.f(3)

NAME
dsymv.f -

SYNOPSIS
Functions/Subroutines
subroutine dsymv (UPLO, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY)
DSYMV

Function/Subroutine Documentation
subroutine dsymv (characterUPLO, integerN, double precisionALPHA, double precision, dimension(lda,*)A, integerLDA, double precision,
dimension(*)X, integerINCX, double precisionBETA, double precision, dimension(*)Y, integerINCY)
DSYMV Purpose:

DSYMV  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.

Parameters:
UPLO

UPLO is CHARACTER*1
On entry, UPLO specifies whether the upper or lower
triangular part of the array A is to be referenced as
follows:

UPLO = 'U' or 'u'   Only the upper triangular part of A
is to be referenced.

UPLO = 'L' or 'l'   Only the lower triangular part of A
is to be referenced.

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.

A

A is DOUBLE PRECISION array of DIMENSION ( LDA, n ).
Before entry with  UPLO = 'U' or 'u', the leading n by n
upper triangular part of the array A must contain the upper
triangular part of the symmetric matrix and the strictly
lower triangular part of A is not referenced.
Before entry with UPLO = 'L' or 'l', the leading n by n
lower triangular part of the array A must contain the lower
triangular part of the symmetric matrix and the strictly
upper triangular part of A is not referenced.

LDA

LDA is INTEGER
On entry, LDA specifies the first dimension of A as declared
in the calling (sub) program. LDA must be at least
max( 1, n ).

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

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 153 of file dsymv.f.

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

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

## Check Out this Related Man Page

```DSYMV(l)							   BLAS routine 							  DSYMV(l)

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

SYNOPSIS
SUBROUTINE DSYMV ( UPLO, N, ALPHA, A, LDA, X, INCX, BETA, Y, INCY )

DOUBLE	PRECISION ALPHA, BETA

INTEGER	INCX, INCY, LDA, N

CHARACTER*1	UPLO

DOUBLE	PRECISION A( LDA, * ), X( * ), Y( * )

PURPOSE
DSYMV  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.

PARAMETERS
UPLO   - CHARACTER*1.
On entry, UPLO specifies whether the upper or lower triangular part of the array A is to be referenced as follows:

UPLO = 'U' or 'u'   Only the upper triangular part of A is to be referenced.

UPLO = 'L' or 'l'   Only the lower triangular part of A is to be referenced.

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.

A      - DOUBLE PRECISION array of DIMENSION ( LDA, n ).
Before entry with  UPLO = 'U' or 'u', the leading n by n upper triangular part of the array A must contain the upper triangular part
of the symmetric matrix and the strictly lower triangular part of A is not referenced.  Before entry with UPLO =	'L'  or  'l',  the
leading  n by n lower triangular part of the array A must contain the lower triangular part of the symmetric matrix and the strictly
upper triangular part of A is not referenced.  Unchanged on exit.

LDA    - INTEGER.
On entry, LDA specifies the first dimension of A as declared in the calling (sub) program. LDA  must  be	at  least  max(  1,  n	).
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							  DSYMV(l)```
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