geqrf_batch (Buffer Strided Version)
Computes the batch of QR factorizations of a batch of general m-by-n matrices. This routine belongs to the
oneapi::mkl::lapack
namespace.Description
The routine forms the
Q
i
R
i
factorizations
of a general m
-by-n
matrices A
i
. No pivoting is
performed.The routine does not form the matrix
Q
i
explicitly.
Instead, Q
i
is represented as a product of min(m
,
n
) elementary reflectors. Routines are provided to work with
Q
i
in this representation.API
Syntax
namespace oneapi::mkl::lapack {
void geqrf_batch(sycl::queue &queue,
std::int64_t m,
std::int64_t n,
sycl::buffer<T> &a,
std::int64_t lda,
std::int64_t stride_a,
sycl::buffer<T> &tau,
std::int64_t stride_tau,
std::int64_t batch_size,
sycl::buffer<T> &scratchpad, std::int64_t scratchpad_size)
}
This function supports the following precisions and devices:
T | Devices supported |
---|---|
float | CPU and GPU |
double | CPU and GPU |
std::complex<float> | CPU and GPU |
std::complex<double> | CPU and GPU |
Input Parameters
- queue
- Device queue where calculations will be performed.
- m
- The number of rows in the matricesAi(0 ≤ m).
- n
- The number of columns in the matricesAi(0 ≤ n).
- a
- Array holding input matricesAi.
- lda
- The leading dimension ofAi.
- stride_a
- The stride between the beginnings of matricesAiinside the batch arraya.
- stride_tau
- The stride between the beginnings of arraystauiinside the arraytau.
- batch_size
- The number of problems in a batch.
- scratchpad
- Scratchpad memory to be used by 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 geqrf_batch_scratchpad_size (Strided Version).
Output Parameters
- a
- Overwritten by the factorization data as follows:The elements on and above the diagonal of the array contain themin(m,n)-by-nupper trapezoidal matricesRi(Riis upper triangular ifm ≥ n); the elements below the diagonal, with the array taui, present the orthogonal matrixQias a product ofmin(m,n)elementary reflectors.
- tau
- Array to store batch oftaui, each of sizemin(m,n), containing scalars that define elementary reflectors for the matricesQiin its decomposition in a product of elementary reflectors.
Exceptions
Exception | Description |
---|---|
mkl::lapack::batch_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 = -n , the n -th parameter had an illegal value.If info equals the value passed as scratchpad size, and detail() returns non-zero, then the passed scratchpad is of insufficient size, and the required size should be not less than the value returned by the detail() method of the exception object. |