getrf_batch (USM Strided Version)

Computes the batch of LU factorizations of a general m-by-n matrices. This routine belongs to the oneapi::mkl::lapacknamespace.

Syntax

cl::sycl::event getrf_batch(cl::sycl::queue &queue, std::int64_t m, std::int64_t n, T *a, std::int64_t lda, std::int64_t stride_a, std::int64_t *ipiv, std::int64_t stride_ipiv, std::int64_t batch_size, T *scratchpad, std::int64_t scratchpad_size, const cl::sycl::vector_class<cl::sycl::event> &events = {})

Function supports the following precisions and devices.

T

Devices supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

std::complex<float>

Host, CPU, and GPU

std::complex<double>

Host, CPU, and GPU

Description

The routine computes the LU factorizations of a batch of general m-by-n matrices Ai, as

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Where Pi is a permutation matrix, Li is lower triangular with unit diagonal elements (lower trapezoidal if m > n) and Ui is upper triangular (upper trapezoidal if m < n). The routine uses partial pivoting with row interchanges.

Input Parameters

queue

Device queue where calculations will be performed.

m

The number of rows in the matrices Ai (0 m).

n

The number of columns in the matrices Ai (0 n).

a

Array holding input matrices Ai.

lda

The leading dimension of Ai .

stride_a

The stride between the beginnings of matrices Ai inside the batch array a.

stride_ipiv

The stride between the beginnings of arrays ipivi inside the array ipiv.

batch_size

Specifies the number of problems in a batch.

scratchpad

Scratchpad memory to be used by 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 getrf_batch_scratchpad_size (Strided Version).

events

List of events to wait for before starting computation. Defaults to empty list.

Output Parameters

a

Overwritten by Li and Ui. The unit diagnonal elements of Li are not stored.

ipiv

Array containing the batch of the pivot indices ipivi each of size at least max(1,min(m,n)); for 1 ≤ kmin(m,n), row k of Ai was interchanged with row ipivi(k).

Exceptions

mkl::lapack::batch_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 = -n, the n-th parameter had an illegal value. If info equals the value passed as scratchpad size, and detail() returns non-zero, then the passed scratchpad is of insufficient size, and the required size should be not less then value returned by the detail() method of the exception object. If info is zero, then the diagonal element of some of Ui is zero, and the solve could not be completed. The indexes of such matrices in the batch can be obtained with the ids() method of the exception object. You can obtain the indexes of the first zero diagonal elements in these Ui matrices using the infos() method of the exception object.

Return Values

Output event to wait on to ensure computation is complete.