getrf¶

Computes the LU factorization of a general m-by-n matrix.

getrf supports the following precisions.

T

float

double

std::complex<float>

std::complex<double>

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.

getrf (BUFFER Version)¶

Syntax

void onemkl::lapack::getrf(cl::sycl::queue &queue, std::int64_t m, std::int64_t n, cl::sycl::buffer<T, 1> &a, std::int64_t lda, cl::sycl::buffer<std::int64_t, 1> &ipiv, cl::sycl::buffer<T, 1> &scratchpad, std::int64_t scratchpad_size)¶

Input Parameters

queue: The queue where the routine should be executed.
m: The number of rows in the matrix A (0≤m).
n: The number of columns in A(0≤n).
a: Buffer holding input matrix A. The buffer a contains the matrix A. The second dimension of a must be at least max(1, n).
lda: The leading dimension of a.
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_scratchpad_size function.

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).
scratchpad: Buffer holding scratchpad memory to be used by routine for storing intermediate results.

Throws

onemkl::lapack::exception

Exception is thrown in case of problems happened during calculations. The info code of the problem can be obtained by get_info() method of 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 equals to value passed as scratchpad size, and get_detail() returns non zero, then passed scratchpad is of insufficient size, and required size should not be less than value return by get_detail() method of exception object.

getrf (USM Version)¶