Visible to Intel only — GUID: GUID-8CAC9131-E361-446C-855E-2AFA06F0E132
Visible to Intel only — GUID: GUID-8CAC9131-E361-446C-855E-2AFA06F0E132
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, std::int64_t n, sycl::buffer<T> &a, std::int64_t lda, sycl::buffer<T> &tau, sycl::buffer<T> &scratchpad, std::int64_t scratchpad_size) }
orgtr supports the following precisions 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 function
- n
-
The order of matrix Q (0 ≤ n).
- a
-
The buffer a returned by the sytrd function. The second dimension of a must be at least max(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 |
---|---|
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. |