orgtr#
Generates the real orthogonal matrix Q determined by sytrd. This routine belongs to the oneapi::mkl::lapack
namespace.
Description#
The routine explicitly generates the n
-by-n
orthogonal matrix
Q
formed by sytrd when reducing a real symmetric matrix A
to tridiagonal form: A = Q*T*QT
. Use this routine after a call to sytrd.
API#
Syntax#
namespace oneapi::mkl::lapack {
void orgtr(sycl::queue &queue,
mkl::uplo uplo,
int64_t n,
sycl::buffer<T> &a,
int64_t lda,
sycl::buffer<T> &tau,
sycl::buffer<T> &scratchpad,
int64_t scratchpad_size)
}
orgtr
supports the following precisions and devices:
T |
Devices supported |
---|---|
|
CPU |
|
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 function
- n
The order of matrix
Q
(0 ≤ n
).- a
The buffer
a
returned by the sytrd function. The second dimension ofa
must be at leastmax(1, n)
.- tau
Buffer holding
tau
returned by the sytrd function.- lda
The leading dimension of
a
(lda ≥ n
).- scratchpad
Buffer holding 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 orgtr_scratchpad_size function.
Output Parameters#
- a
Overwritten by the orthogonal matrix
Q
.
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 |