Developer Reference

  • 2020.2
  • 07/15/2020
  • Public Content
Contents

?syr2

Performs
a rank-2 update of a symmetric matrix.

Syntax

call ssyr2
(
uplo
,
n
,
alpha
,
x
,
incx
,
y
,
incy
,
a
,
lda
)
call dsyr2
(
uplo
,
n
,
alpha
,
x
,
incx
,
y
,
incy
,
a
,
lda
)
call syr2
(
a
,
x
,
y
[
,
uplo
]
[
,
alpha
]
)
Include Files
  • mkl.fi
    ,
    blas.f90
Description
The
?syr2
routines perform a matrix-vector operation defined as
A
:=
alpha
*
x
*
y
'+
alpha
*
y
*
x
' +
A
,
where:
alpha
is scalar,
x
and
y
are
n
-element vectors,
A
is an
n
-by-
n
symmetric matrix.
Input Parameters
uplo
CHARACTER*1
.
Specifies whether the upper or lower triangular part of the array
a
is used.
If
uplo
=
'U'
or
'u'
, then the upper triangular part of the array
a
is used.
If
uplo
=
'L'
or
'l'
, then the low triangular part of the array
a
is used.
n
INTEGER
.
Specifies the order of the matrix
A
. The value of
n
must be at least zero.
alpha
REAL
for
ssyr2
DOUBLE PRECISION
for
dsyr2
Specifies the scalar
alpha
.
x
REAL
for
ssyr2
DOUBLE PRECISION
for
dsyr2
Array, size at least
(1 + (
n
- 1)*abs(
incx
))
. Before entry, the incremented array
x
must contain the
n
-element vector
x
.
incx
INTEGER
.
Specifies the increment for the elements of
x
.
The value of
incx
must not be zero.
y
REAL
for
ssyr2
DOUBLE PRECISION
for
dsyr2
Array, size at least
(1 + (
n
- 1)*abs(
incy
))
. Before entry, the incremented array
y
must contain the
n
-element vector
y
.
incy
INTEGER
.
Specifies the increment for the elements of
y
. The value of
incy
must not be zero.
a
REAL
for
ssyr2
DOUBLE PRECISION
for
dsyr2
Array, size
(
lda
,
n
)
.
Before entry with
uplo
=
'U'
or
'u'