Developer Reference

Contents

?lagsy

Generates a symmetric matrix by pre- and post- multiplying a real diagonal matrix with a random unitary matrix .

Syntax

lapack_int
LAPACKE_slagsy
(
int
matrix_layout
,
lapack_int
n
,
lapack_int
k
,
const
float
*
d
,
float
*
a
,
lapack_int
lda
,
lapack_int
*
iseed
);
lapack_int
LAPACKE_dlagsy
(
int
matrix_layout
,
lapack_int
n
,
lapack_int
k
,
const
double
*
d
,
double
*
a
,
lapack_int
lda
,
lapack_int
*
iseed
);
lapack_int
LAPACKE_clagsy
(
int
matrix_layout
,
lapack_int
n
,
lapack_int
k
,
const
float
*
d
,
lapack_complex_float
*
a
,
lapack_int
lda
,
lapack_int
*
iseed
);
lapack_int
LAPACKE_zlagsy
(
int
matrix_layout
,
lapack_int
n
,
lapack_int
k
,
const
double
*
d
,
lapack_complex_double
*
a
,
lapack_int
lda
,
lapack_int
*
iseed
);
Include Files
  • mkl.h
Description
The
?lagsy
routine generates a symmetric matrix
A
by pre- and post- multiplying a real diagonal matrix
D
with a random matrix
U
:
A
:=
U
*
D
*
U
T
,
where
U
is orthogonal for real flavors and unitary for complex flavors. The semi-bandwidth may then be reduced to
k
by additional unitary transformations.
Input Parameters
A
<datatype>
placeholder, if present, is used for the C interface data types in the C interface section above. See C Interface Conventions for the C interface principal conventions and type definitions.
n
The order of the matrix
A
(
n
0
).
k
The number of nonzero subdiagonals within the band of
A
(
0
k
n
-1)
.
d
The array
d
with the dimension of (
n
) contains the diagonal elements of the diagonal matrix
D
.
lda
The leading dimension of the array
a
(
lda
n
).
iseed
The array
iseed
with the dimension of 4 contains the seed of the random number generator. The elements must be between 0 and 4095 and
iseed
[3]
must be odd.
Output Parameters
a
The array
a
of size max (1,
lda
*
n
)
contains the generated symmetric
n
-by-
n
matrix
D
.
iseed
The array
iseed
contains the updated seed on exit.
Return Values
This function returns a value
info
.
If
info
= 0
, the execution is successful.
If
info
< 0
, the
i
-th parameter had an illegal value.
If
info
= -1011
, memory allocation error occurred.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.