ungtr#
Generates the complex unitary matrix Q determined by
hetrd. This routine belongs to the oneapi::mkl::lapack namespace.
Description#
The routine explicitly generates the n-by-n unitary matrix
Q formed by hetrd when reducing a complex Hermitian matrix A to tridiagonal form: A = Q*T*QH. Use this routine after a call to
hetrd.
API#
Syntax#
namespace oneapi::mkl::lapack {
void ungtr(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)
}
ungtr supports the following precision 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 hetrd function.
- n
The order of matrix
Q(0 ≤ n).- a
The buffer
areturned by the hetrd function. The size ofamust be at leastlda*n.- lda
The leading dimension of
a(lda ≥ n).- tau
The buffer tau returned by the hetrd function. The dimension of tau must be at least
max(1,n-1).- 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 ungtr_scratchpad_size function.
Output Parameters#
- a
Overwritten by the unitary 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 |