Visible to Intel only — GUID: GUID-7A98463D-0C29-4374-960D-943D59CE22B5
Visible to Intel only — GUID: GUID-7A98463D-0C29-4374-960D-943D59CE22B5
getrf
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
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). The routine uses partial pivoting, with row interchanges.
API
Syntax
namespace oneapi::mkl::lapack { void getrf(sycl::queue &queue, std::int64_t m, std::int64_t n, sycl::buffer<T> &a, std::int64_t lda, sycl::buffer<T> &ipiv, sycl::buffer<T> &scratchpad, std::int64_t scratchpad_size) }
getrf supports the following precisions and devices.
T |
Devices supported |
---|---|
float |
CPU and GPU |
double |
CPU and GPU |
std::complex<float> |
CPU and GPU |
std::complex<double> |
CPU and GPU |
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 A(0 ≤ n). |
a |
Buffer holding array holding input matrix A. The second dimension of a must be at least max(1, n). |
lda |
The leading dimension of a. |
scratchpad |
Buffer holding 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 should not be less than the value returned by the getrf_scratchpad_size function. |
Output Parameters
a |
Overwritten by L and U. The unit diagonal elements of L are not stored. |
ipiv |
Buffer holding array of 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). |
info |
Buffer containing error information. If info=0, execution is successful. 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. |
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 should not be less than the value returned by the detail() method of the exception object. |