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 QiRi factorizations
of a general m-by-n matrices Ai. No pivoting is
performed.
The routine does not form the matrix Qi explicitly.
Instead, Qi is represented as a product of min(m,
n) elementary reflectors. Routines are provided to work with
Qi in this representation.
API#
Syntax#
namespace oneapi::mkl::lapack {
void geqrf_batch(sycl::queue &queue,
int64_t m,
int64_t n,
sycl::buffer<T> &a,
int64_t lda,
int64_t stride_a,
sycl::buffer<T> &tau,
int64_t stride_tau,
int64_t batch_size,
sycl::buffer<T> &scratchpad, int64_t scratchpad_size)
}
This function supports the following precisions and devices:
T |
Devices supported |
|---|---|
|
CPU and GPU* |
|
CPU and GPU* |
|
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.
- m
The number of rows in the matrices
Ai (m ≥ 0).- n
The number of columns in the matrices
Ai (n ≥ 0).- a
Array holding input matrices
Ai.- lda
The leading dimension of
Ai (lda≥max(1, m)).- stride_a
The stride between the beginnings of matrices
Ai inside the batch arraya(stride_a≥max(1, lda * n)).- stride_tau
The stride between the beginnings of arrays
taui inside the arraytau(stride_tau≥max(1, min(m,n))).- batch_size
The number of problems in a batch (
batch_size≥ 0).- 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 type
T. 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 the
min(m,n)-by-nupper trapezoidal matricesRi (Ri is upper triangular ifm ≥ n); the elements below the diagonal, with the array taui, present the orthogonal matrixQi as a product ofmin(m,n)elementary reflectors.- tau
Array to store batch of
taui, each of sizemin(m,n), containing scalars that define elementary reflectors for the matricesQi in its decomposition in a product of elementary reflectors.
Exceptions#
Exception |
Description |
|---|---|
|
This exception is thrown when problems occur during calculations. You can obtain the info code of the problem using the If If |