getrfnp#

Computes the LU factorization of a general m-by-n matrix without pivoting. 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 = L*U,

where 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 does not use pivoting.

API#

Syntax#

namespace oneapi::mkl::lapack {
  void getrfnp(sycl::queue &queue,
  int64_t m,
  int64_t n,
  sycl::buffer<T> &a,
  int64_t lda,
  sycl::buffer<T> &scratchpad,
  int64_t scratchpad_size)
}

getrfnp 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*

*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 (m 0).

n

The number of columns in A (n 0).

a

Buffer holding input matrix A. The array must be of size at least lda * max(1, n).

lda

The leading dimension of a (ldamax(1, m)).

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 must not be less than the value returned by the getrfnp_scratchpad_size function.

Output Parameters#

a

Overwritten by L and U. The unit diagonal elements of L are not stored.

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.