Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

  • 2021.1
  • 12/04/2020
  • Public Content
Contents

?sytrs_rook

Solves a system of linear equations with a UDU- or LDL-factored symmetric coefficient matrix.

Syntax

lapack_int
LAPACKE_ssytrs_rook
(
int
matrix_layout
,
char
uplo
,
lapack_int
n
,
lapack_int
nrhs
,
const
float
*
a
,
lapack_int
lda
,
const
lapack_int
*
ipiv
,
float
*
b
,
lapack_int
ldb
);
lapack_int
LAPACKE_dsytrs_rook
(
int
matrix_layout
,
char
uplo
,
lapack_int
n
,
lapack_int
nrhs
,
const
double
*
a
,
lapack_int
lda
,
const
lapack_int
*
ipiv
,
double
*
b
,
lapack_int
ldb
);
lapack_int
LAPACKE_csytrs_rook
(
int
matrix_layout
,
char
uplo
,
lapack_int
n
,
lapack_int
nrhs
,
const
lapack_complex_float
*
a
,
lapack_int
lda
,
const
lapack_int
*
ipiv
,
lapack_complex_float
*
b
,
lapack_int
ldb
);
lapack_int
LAPACKE_zsytrs_rook
(
int
matrix_layout
,
char
uplo
,
lapack_int
n
,
lapack_int
nrhs
,
const
lapack_complex_double
*
a
,
lapack_int
lda
,
const
lapack_int
*
ipiv
,
lapack_complex_double
*
b
,
lapack_int
ldb
);
Include Files
  • mkl.h
Description
The routine solves a system of linear equations
A*X
 =
B
 with a symmetric matrix
A
, using the factorization
A
 =
U*D*U
T
 or
A
 =
L*D*L
T
 computed by
?sytrf_rook
.
Input Parameters
matrix_layout
Specifies whether matrix storage layout for array
b
 is row major (
LAPACK_ROW_MAJOR
) or column major (
LAPACK_COL_MAJOR
).
uplo
Must be
'U'
 or
'L'
.
Indicates how the input matrix
A
 has been factored:
If
uplo
 =
'U'
, the factorization is of the form
A
 =
U*D*U
T
.
If
uplo
 =
'L'
, the factorization is of the form
A
 =
L*D*L
T
.
n
The order of matrix
A
;
n
≥
 0.
nrhs
The number of right-hand sides;
nrhs
≥
 0.
ipiv
Array, size at least
max(1,
n
)
. The
ipiv
 array, as returned by
?sytrf_rook
.
a
,
b
Arrays:
a
, size (
lda
*
n
)
,
b
 size (
ldb
*
nrhs
)
.
The array
a
 contains the block diagonal matrix
D
 and the multipliers used to obtain
U
 or
L
 as computed by
?sytrf_rook
 (see
uplo
).
The array
b
 contains the matrix
B
 whose columns are the right-hand sides for the system of equations.
lda
The leading dimension of
a
;
lda
≥
 max(1,
n
)
.
ldb
The leading dimension of
b
;
ldb
≥
 max(1,
n
) for column major layout and
ldb
≥
nrhs
) for row major layout
.
Output Parameters
b
Overwritten by the solution matrix
X
.
Return Values
This function returns a value
info
.
If
info
=0
, the execution is successful.
If
info
 =
-i
, the
i
-th parameter had an illegal value.
Application Notes
The total number of floating-point operations for one right-hand side vector is approximately
2
n
2
 for real flavors or
8
n
2
 for complex flavors.

Product and Performance Information

1

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