ormrq
Multiplies a real matrix by the orthogonal matrix Q of the RQ
factorization formed by
gerqf
.Description
The routine multiplies a real
m
-by-n
matrix C
by Q
or
Q
T
, where Q
is the real orthogonal matrix defined as
a product of k
elementary reflectors H
i
:
Q = H1H2 ... Hk
as returned by the RQ
factorization routine
gerqf.Depending on the parameters
side
and trans
, the routine can
form one of the matrix products Q*C
, QT*C
, C*Q
, or
C*QT
(overwriting the result over C
).API
Syntax
namespace oneapi::mkl::lapack {
void ormrq(cl::sycl::queue &queue,
mkl::side side,
mkl::transpose trans,
std::int64_t m,
std::int64_t n,
std::int64_t k,
cl::sycl::buffer<T> &a,
std::int64_t lda,
cl::sycl::buffer<T> &tau,
cl::sycl::buffer<T> &c,
std::int64_t ldc,
cl::sycl::buffer<T> &scratchpad,
std::int64_t scratchpad_size)
}
ormrq
supports the following precisions and devices:T | Devices supported |
---|---|
float | Host and CPU |
double | Host and CPU |
Input Parameters
- queue
- Device queue where calculations will be performed.
- side
- Ifside=mkl::side::left,QorQTis applied toCfrom the left. Ifside=mkl::side::right,QorQTis applied toCfrom the right.
- trans
- Iftrans=mkl::transpose::trans, the routine multipliesCbyQ.Iftrans=mkl::transpose::nontrans, the routine multipliesCbyQT.
- m
- The number of rows in the matrixA(0≤m).
- n
- The number of columns in the matrixA(0≤n≤m).
- k
- The number of elementary reflectors whose product defines the matrixQ(0≤k≤n).
- a
- Buffer holding the result of the gerqf function. The second dimension ofamust be at leastmax(1,k).
- lda
- The leading dimension of a.
- tau
- Buffer holding tau returned by the gerqf function.
- c
- Buffer holding the matrixC. The second dimension of c must be at leastmax(1,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 typeT. Size should not be less than the value returned by the ormrq_scratchpad_size function.
Output Parameters
- c
- Overwritten by the productQ*C,QT*C,C*Q, orC*QT(as specified by side and trans).
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. |
Application Notes
The complex counterpart of this routine is unmrq.