ungqr_batch (Buffer Strided Version)#
Generates the complex unitary matrices Qi of the batch of QR
factorizations formed by geqrf_batch function (Buffer stride version).
This routine belongs to the oneapi::mkl::lapack namespace.
Description#
The routine generates the wholes or parts of m-by-m unitary
matrix Qi of the QR factorization formed by the
geqrf_batch (Buffer Strided Version)
function.
Usually Qi is determined from the QR factorization
of an m by p matrix Ai with m ≥ p. To compute
the whole matrices Qi, use:
ungqr_batch(queue, m, m, p, a, ...)
To compute the leading p columns of Qi (which form
an orthonormal basis in the space spanned by the columns of
Ai):
ungqr_batch(queue, m, p, p, a, ...)
To compute the matrix Qik of the QR
factorization of the leading k columns of the matrices
Ai:
ungqr_batch(queue, m, m, k, a, ...)
To compute the leading k columns of Qik
(which form an orthonormal basis in the space spanned by the leading
k columns of the matrices Ai):
ungqr_batch(queue, m, k, k, a, ...)
API#
Syntax#
namespace oneapi::mkl::lapack {
void ungqr_batch(sycl::queue &queue,
int64_t m,
int64_t n,
int64_t k,
sycl::buffer<T> &a,
int64_t lda,
int64_t stride_a,
sycl::buffer<T> &tau,
int64_t stride_tau,
int64_t batch_size,
sycl::buffer<T> &scratchpad,
int64_t scratchpad_size)
}
This function supports the following precisions and devices:
T |
Devices supported |
|---|---|
|
CPU and GPU* |
|
CPU and GPU* |
*Interface support only; all computations are performed on the CPU.
Input Parameters#
- queue
Device queue where calculations will be performed.
- m
The number of rows in the matrices
Ai (m ≥ 0).- n
The number of columns in the matrices
Ai (n ≥ 0).- k
the number of elementary reflectors whose product defines the matrices
Qi (0 ≤k≤n) .- a
Array resulting after a call to geqrf_batch (Buffer Strided Version).
- lda
The leading dimension of
Ai (lda≥max(1,m)).- stride_a
The stride between the beginnings of matrices
Ai inside the batch arraya(stride_a≥max(1, lda * n)).- tau
Array resulting after a call to geqrf_batch (Buffer Strided Version).
- stride_tau
The stride between the beginnings of arrays
taui inside the arraytau(stride_tau≥max(1, min(m,n))).- batch_size
The number of problems in a batch (
batch_size≥ 0).- 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 ungqr_batch_scratchpad_size (Strided Version).
Output Parameters#
- a
Array data is overwritten by a batch of
nleading columns of them-by-munitary matricesQi.
Exceptions#
Exception |
Description |
|---|---|
|
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 If |