unmqr (USM Version)

oneMKL - Data Parallel C++ Developer Reference

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ID 772045

Date 6/24/2024

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unmqr (USM Version)

Multiplies a complex matrix by the unitary matrix Q of the QR factorization formed by the geqrf (USM Version) function. This routine belongs to the oneapi::mkl::lapack namespace.

Description
API

Description

The routine multiplies a complex matrix C by Q or Q^T, where Q is the orthogonal matrix Q of the QR factorization formed by the routine geqrf (USM Version).

Depending on the parameters side and trans, the routine can form one of the matrix products Q*C, Q^T*C, C*Q, or C*Q^T (overwriting the result on C).

API

Syntax

namespace oneapi::mkl::lapack {
  sycl::event unmqr(sycl::queue &queue,
  mkl::side side,
  mkl::transpose trans,
  std::int64_t m,
  std::int64_t n,
  std::int64_t k,
  T *a,
  std::int64_t lda,
  T *tau,
  T *c,
  std::int64_t ldc,
  T *scratchpad,
  std::int64_t scratchpad_size,
  const std::vector<sycl::event> &events = {})
}

unmqr (USM version) supports the following precisions and devices:

T	Devices supported
`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.

side

If side = mkl::side::left, Q or Q^T is applied to C from the left. If side = mkl::side::right, Q or Q^T is applied to C from the right.

trans

If trans=mkl::transpose::trans, the routine multiplies C by Q.

If trans=mkl::transpose::nontrans, the routine multiplies C by Q^T.

m

The number of rows in the matrix A (0 ≤ m).

n

The number of columns in the matrix A (0 ≤ n ≤ m).

k

The number of elementary reflectors whose product defines the matrix Q (0 ≤ k ≤ n).

a

The pointer to the result of the geqrf (USM Version) function. The second dimension of a must be at least max(1,k).

lda

The leading dimension of a.

tau

The pointer to tau returned by the geqrf (USM Version) function.

c

The pointer to the matrix C. The second dimension of c must be at least max(1,n).

ldc

The leading dimension of c.

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 should not be less than the value returned by the unmqr_scratchpad_size function.

events

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

Output Parameters

c: Overwritten by the product Q*C, Q^T*C, C*Q, or C*Q^T (as specified by side and trans).

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` 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.

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 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.

Return Values

Output event to wait on to ensure computation is complete.

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oneMKL - Data Parallel C++ Developer Reference

unmqr (USM Version)

Description

API