Developer Reference for Intel® oneAPI Math Kernel Library - C

Developer Reference

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

?getf2

Computes the LU factorization of a general m-by-n matrix using partial pivoting with row interchanges (unblocked algorithm).

Syntax

lapack_int
LAPACKE_sgetf2
(
int
matrix_layout
,
lapack_int
m
,
lapack_int
n
,
float
*
a
,
lapack_int
lda
,
lapack_int
*
ipiv
);
lapack_int
LAPACKE_dgetf2
(
int
matrix_layout
,
lapack_int
m
,
lapack_int
n
,
double
*
a
,
lapack_int
lda
,
lapack_int
*
ipiv
);
lapack_int
LAPACKE_cgetf2
(
int
matrix_layout
,
lapack_int
m
,
lapack_int
n
,
lapack_complex_float
*
a
,
lapack_int
lda
,
lapack_int
*
ipiv
);
lapack_int
LAPACKE_zgetf2
(
int
matrix_layout
,
lapack_int
m
,
lapack_int
n
,
lapack_complex_double
*
a
,
lapack_int
lda
,
lapack_int
*
ipiv
);
Include Files
  • mkl.h
Description
The routine computes the
LU
 factorization of a general
m
-by-
n
 matrix
A
 using partial pivoting with row interchanges. The factorization has the form
A
 =
P
*
L
*
U
where
p
 is a permutation matrix,
L
 is lower triangular with unit diagonal elements (lower trapezoidal if
m
 >
n
) and
U
 is upper triangular (upper trapezoidal if
m
 <
n
).
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.
m
The number of rows in the matrix
A
 (
m
≥
 0
).
n
The number of columns in
A
 (
n
≥
 0
).
a
Array, size at least
max(1,
lda
*
n
)
 for column major and
max(1,
lda
*
m
)
 for row major layout. Array
a
 contains the
m
-by-
n
 matrix
A
.
lda
The leading dimension of
a
; at least max(1,
m
)
for column major layout and max(1,
n
) for row major layout
.
Output Parameters
a
Overwritten by
L
 and
U
. The unit diagonal elements of
L
 are not stored.
ipiv
Array, size at least
max(1,min(
m
,
n
))
.
The pivot indices: for
1 ≤ i ≤
n
, row
i
 was interchanged with row
ipiv
(
i
).
Return Values
This function returns a value
info
.
If
info
 =
-i
, the
i
-th parameter had an illegal value.
If
info
 =
i
 >0
,
u
i
i
 is 0. The factorization has been completed, but
U
 is exactly singular. Division by 0 will occur if you use the factor
U
 for solving a system of linear equations.
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.