ormqr#
Multiplies a real matrix by the orthogonal matrix Q of the QR factorization formed by geqrf. This routine belongs to the oneapi::mkl::lapack namespace.
Description#
The routine multiplies a real matrix C by Q or
QT, where Q is the orthogonal matrix Q of the
QR factorization formed by the routine
geqrf.
Depending on the parameters left_right and trans, the routine
can form one of the matrix products Q*C, QT*C, C*Q, or
C*QT (overwriting the result on C).
API#
Syntax#
namespace oneapi::mkl::lapack {
void ormqr(sycl::queue &queue,
mkl::side side,
mkl::transpose trans,
int64_t m,
int64_t n,
int64_t k,
sycl::buffer<T> &a,
int64_t lda,
sycl::buffer<T> &tau,
sycl::buffer<T> &c,
int64_t ldc,
sycl::buffer<T> &scratchpad,
int64_t scratchpad_size)
}
ormqr supports the following precisions and devices:
T |
Devices supported |
|---|---|
|
CPU and GPU* |
|
CPU and GPU* |
*Hybrid support; some computations are performed on the CPU.
Input Parameters#
- queue
Device queue where calculations will be performed.
- side
If
side=mkl::side::left,QorQT is applied toCfrom the left. Ifside=mkl::side::right,QorQT is applied toCfrom the right.- trans
If
trans=mkl::transpose::trans, the routine multipliesCbyQ.If
trans=mkl::transpose::nontrans, the routine multipliesCbyQT.- m
The number of rows in the matrix
A(0 ≤ m).- n
The number of columns in the matrix
A(0 ≤ n ≤ m).- k
The number of elementary reflectors whose product defines the matrix
Q(0 ≤ k ≤ n).- a
Buffer holding the result of the geqrf function. . The size of
amust be at leastlda*k.- lda
The leading dimension of a.
- tau
Buffer holding tau returned by the geqrf function.
- c
Buffer holding the matrix
C. The size ofcmust be at leastldc*n.- ldc
The leading dimension of c.
- 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 ormqr_scratchpad_size function.
Output Parameters#
- c
Overwritten by the product
Q*C,QT*C,C*Q, orC*QT (as specified by left_right and trans).
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 |