orgqr_batch (Buffer Strided Version)

Generates the real orthogonal matrices Qi of the batch QR factorizations formed by geqrf_batch (Buffer Strided Version). This routine belongs to the oneapi::mkl::lapacknamespace.

Syntax

void orgqr_batch(cl::sycl::queue &queue, std::int64_t m, std::int64_t n, std::int64_t k, cl::sycl::buffer<T> &a, std::int64_t lda, std::int64_t stride_a, cl::sycl::buffer<T> &tau, std::int64_t stride_tau, std::int64_t batch_size, cl::sycl::buffer<T> &scratchpad, std::int64_t scratchpad_size)

Function supports the following precisions and devices.

T

Devices supported

float

Host, CPU, and GPU

double

Host, CPU, and GPU

Description

The routine generates the wholes or parts of the orthogonal matrices Q1 of the batch of QR factorizations formed by the routine geqrf_batch (Buffer Strided Version). Usually, Q1 is determined from the QR factorization of an m-by-p matrix A1 with mp.

To compute the whole matrices Q1, use:

orgqr_batch(queue, m, m, p, a, ...)

To compute the leading p columns of Q1 (which form an orthonormal basis in the space spanned by the columns of A1):

orgqr_batch(queue, m, p, p, a, ...)

To compute the matrices Q1k of the QR factorizations of leading ``\ k columns of the matrices ``A1:

orgqr_batch(queue, m, m, k, a, ...)

To compute the leading k columns of Q1k (which form an orthonormal basis in the space spanned by leading k columns of the matrices A1):

orgqr_batch(queue, m, k, k, a, ...)

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).

k

the number of elementary reflectors whose product defines the matrices Qi (0 ≤ kn) .

a

Array resulting after a call to geqrf_batch (Buffer Strided Version).

lda

The leading dimension of Ai (ldam).

stride_a

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

tau

Array resulting after a call to geqrf_batch (Buffer Strided Version).

stride_tau

The stride between the beginnings of arrays taui inside the array tau.

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 orgqr_batch_scratchpad_size (Strided Version).

Output Parameters

a

Array data is overwritten by a batch of n leading columns of the m-by-m orthogonal matrices Qi.

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.