orgtr (USM Version)
Generates the real orthogonal matrix Q determined by the
sytrd
(USM
Version) function. This routine belongs to the oneapi::mkl::lapack
namespace.Description
The routine explicitly generates the
n
-by-n
orthogonal matrix
Q
formed by sytrd (USM Version) when
reducing a real symmetric matrix A
to tridiagonal form:
A = Q*T*QT
. Use this routine after a call to sytrd (USM Version).API
Syntax
namespace oneapi::mkl::lapack {
sycl::event orgtr(sycl::queue &queue,
mkl::uplo uplo,
std::int64_t n,
T *a,
std::int64_t lda,
T *tau,
T *scratchpad,
std::int64_t scratchpad_size,
const std::vector<sycl::event> &events = {})
}
orgtr
(USM version) supports the following precision and
devices.T | Devices Supported |
---|---|
float | CPU |
double | CPU |
Input Parameters
- queue
- Device queue where calculations will be performed.
- uplo
- Must be uplo::upper or uplo::lower. Uses the same uplo as supplied to the sytrd (USM Version) function
- n
- The order of matrixQ(0 ≤ n).
- a
- The pointerareturned by the sytrd (USM Version) function. The second dimension ofamust be at leastmax(1, n).
- tau
- The pointer totaureturned by the geqrf (USM Version) function.
- lda
- The leading dimension ofa(lda ≥ n).
- 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 typeT. Size should not be less than the value returned by the orgtr_scratchpad_size function.
- events
- List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
- a
- Overwritten by the orthogonal matrixQ.
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.