ormqr¶

Multiplies a real matrix by the orthogonal matrix Q of the QR factorization formed by geqrf.

ormqr supports the following precisions.

T

float

double

std::complex<float>

std::complex<double>

Description

The routine multiplies a real matrix C by Q or Q^T, 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).

ormqr (BUFFER Version)¶

Syntax

void onemkl::lapack::ormqr(cl::sycl::queue &queue, onemkl::side left_right, onemkl::transpose trans, std::int64_t m, std::int64_t n, std::int64_t k, cl::sycl::buffer<T, 1> &a, std::int64_t lda, cl::sycl::buffer<T, 1> &tau, cl::sycl::buffer<T, 1> &c, std::int64_t ldc, cl::sycl::buffer<T, 1> &scratchpad, std::int64_t scratchpad_size)¶

Input Parameters

queue

The queue where the routine should be executed.

left_right

If left_right=onemkl::side::left, Q or Q^T is applied to C from the left.

If left_right=onemkl::side::right, Q or Q^T is applied to C from the right.

trans

If trans=onemkl::transpose::trans, the routine multiplies C by Q.

If trans=onemkl::transpose::nontrans, the routine multiplies C by Q^T.

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

The buffer a as returned by geqrf. The second dimension of a must be at least max(1,k).

lda

The leading dimension of a.

tau

The buffer tau as returned by geqrf. The second dimension of a must be at least max(1,k).

c

The buffer c contains the matrix C. The second dimension of c must be at least max(1,n).

ldc

The leading dimension of c.

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 ormqr_scratchpad_size function.

Output Parameters

c: Overwritten by the product Q*C, Q^T*C, C*Q, or C*Q^T (as specified by left_right and trans).
scratchpad: Buffer holding scratchpad memory to be used by routine for storing intermediate results.

Throws

onemkl::lapack::exception

Exception is thrown in case of problems happened during calculations. The info code of the problem can be obtained by get_info() method of exception object:

If info=-i, the i-th parameter had an illegal value.

If info equals to value passed as scratchpad size, and get_detail() returns non zero, then passed scratchpad is of insufficient size, and required size should not be less than value return by get_detail() method of exception object.

ormqr (USM Version)¶