orgbr (USM Version)#
Generates the real orthogonal matrix Q or PT determined
by gebrd (USM Version). This
routine belongs to the oneapi::mkl::lapack namespace.
Description#
The routine generates the whole or part of the orthogonal matrices
Q and PT formed by the gebrd (USM Version)
function. All valid combinations of arguments are described in Input
parameters. In most cases you need the following:
To compute the whole m-by-m matrix Q:
orgbr(queue, generate::q, m, m, n, a, ...)
(note that the array a must have at least m columns).
To form the n leading columns of Q if m > n:
orgbr(queue, generate::q, m, n, n, a, ...)
To compute the whole n-by-n matrix PT:
orgbr(queue, generate::p, n, n, m, a, ...)
(note that the array a must have at least n rows).
To form the m leading rows of PT if m < n:
orgbr(queue, generate::p, m, n, m, a, ...)
API#
Syntax#
namespace oneapi::mkl::lapack {
sycl::event orgbr(sycl::queue &queue,
mkl::generate gen,
int64_t m,
int64_t n,
int64_t k,
T *a,
int64_t lda,
const T *tau,
T *scratchpad,
int64_t scratchpad_size,
const std::vector<sycl::event> &events = {})
}
orgbr (USM version) supports the following precisions and
devices:
T |
Devices supported |
|---|---|
|
CPU |
|
CPU |
Input Parameters#
- queue
Device queue where calculations will be performed.
- gen
Must be
generate::qorgenerate::p.If gen
= generate::q, the routine generates the matrixQ.If gen
= generate::p, the routine generates the matrixPT.- m
The number of rows in the matrix
QorPT to be returned(0 ≤ m).If gen
= generate::q,m ≥ n ≥ min(m, k).If gen
= generate::p,n ≥ m ≥ min(n, k).- n
The number of rows in the matrix
QorPT to be returned(0 ≤ n). See m for constraints.- k
If gen
= generate::q, the number of columns in the originalm-by-k matrix reduced by gebrd (USM Version).If gen
= generate::p, the number of rows in the originalk-by-n matrix reduced by gebrd (USM Version).- a
Pointer to memory returned by gebrd (USM Version).
- lda
The leading dimension of a.
- tau
Pointer to memory of size
min (m,k)if gen= generate::q, and of sizemin(n,k)if gen= generate::p. Scalar factor of the elementary reflectors, as returned by gebrd (USM Version) in the arraytauqortaup.- 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 orgbr_scratchpad_size function.- events
List of events to wait for before starting computation. Defaults to empty list.
Output Parameters#
- a
Overwritten by n leading columns of the m-by-m orthogonal matrix
QorPT (or the leading rows or columns thereof) as specified by gen, m, and n.
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 |
Return Values#
Output event to wait on to ensure computation is complete.