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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 |
|---|---|
float |
CPU |
double |
CPU |
Input Parameters
- queue
-
Device queue where calculations will be performed.
- gen
-
Must be generate::q or generate::p.
If gen= generate::q, the routine generates the matrix Q.
If gen= generate::p, the routine generates the matrix PT.
- m
-
The number of rows in the matrix Q or PT 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 Q or PT to be returned (0 ≤ n). See m for constraints.
- k
-
If gen= generate::q, the number of columns in the original m-by-k matrix reduced by gebrd (USM Version).
If gen= generate::p, the number of rows in the original k-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 size min(n,k) if gen= generate::p. Scalar factor of the elementary reflectors, as returned by gebrd (USM Version) in the array tauq or taup.
- 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 Q or PT (or the leading rows or columns thereof) as specified by gen, m, and n.
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. |
Return Values
Output event to wait on to ensure computation is complete.