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getrf (USM Version)
Computes the LU factorization of a general m-by-n matrix. This routine belongs to the oneapi::mkl::lapack namespace.
Description
The routine computes the LU factorization of a general m-by-n matrix A as
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). The routine uses partial pivoting, with row interchanges.
API
Syntax
namespace oneapi::mkl::lapack {
sycl::event getrf(sycl::queue &queue,
int64_t m,
int64_t n,
T *a,
int64_t lda,
int64_t *ipiv,
T *scratchpad,
int64_t scratchpad_size,
const std::vector<sycl::event> &events = {})
}getrf (USM version) supports the following precisions and devices:
T |
Devices supported |
|---|---|
float |
CPU, GPU* |
double |
CPU, GPU* |
std::complex<float> |
CPU, GPU* |
std::complex<double> |
CPU, GPU* |
*Hybrid support; some computations are performed on the CPU.
Input Parameters
- queue
-
Device queue where calculations will be performed.
- m
-
The number of rows in the matrix A (0 ≤ m).
- n
-
The number of columns in the matrix A (0 ≤ n).
- a
-
Pointer to the array holding input matrix A. The array must be of size at least lda * max(1, n).
- lda
-
The leading dimension of a (lda ≥ max(1, m)).
- scratchpad
-
Pointer to scratchpad memory to be used by the routine for storing intermediate results.
- scratchpad_size
-
Size of scratchpad memory as a number of floating point elements of type T. Size must not be less than the value returned by the getrf_scratchpad_size function.
- events
-
List of events to wait for before starting computation. Defaults to empty list.
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)).
Contains the pivot indices; for 1 ≤ i ≤ min(m,n), row i was interchanged with row ipiv(i).
Exceptions
Exception |
Description |
|---|---|
mkl::lapack::exception |
This exception is thrown when problems occur during calculations. You can obtain the info code of the problem using the info() method of the exception object: If info = -i, the i-th parameter had an illegal value. If info = i, uii 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 is equal to the value passed as scratchpad size, and detail() returns non-zero, then the passed scratchpad has an insufficient size, and the required size must not be less than the value returned by the detail() method of the exception object. |
Return Values
Output event to wait on to ensure computation is complete.