Intel® oneAPI Math Kernel Library (oneMKL) - Data Parallel C++ Developer Reference

Developer Reference

Contents

orgqr_batch (Group Version)

Generates the real orthogonal matrices
Q
i
 of the batch of QR factorizations formed by
geqrf_batch
 (Group Version). This routine belongs to the
oneapi::mkl::lapack
 namespace.

Description

The routine generates the wholes or parts of the
m
-by-
m
 orthogonal matrices
Q
1
 of the batch of QR factorizations formed by the routine geqrf_batch (Group Version). Usually,
Q
1
 is determined from the QR factorization of an
m
-by-
p
 matrix
A
1
 with
m
 ≥
p
.
To compute the whole matrices
Q
1
, use:
orgqr_batch(queue, m, m, p, a, ...)
To compute the leading
p
 columns of
Q
1
 (which form an orthonormal basis in the space spanned by the columns of
A
1
):
orgqr_batch(queue, m, p, p, a, ...)
To compute the matrices
Q
1
k
 of the QR factorizations of leading
k
 columns of the matrices
A
1
:
orgqr_batch(queue, m, m, k, a, ...)
To compute the leading
k
 columns of
Q
1
k
 (which form an orthonormal basis in the space spanned by leading
k
 columns of the matrices
A
1
):
orgqr_batch(queue, m, k, k, a, ...)

API

Syntax
namespace oneapi::mkl::lapack {
  cl::sycl::event orgqr_batch(cl::sycl::queue &queue,
  std::int64_t *m,
  std::int64_t *n,
  std::int64_t *k,
  T **a,
  std::int64_t *lda,
  T **tau,
  std::int64_t group_count,
  std::int64_t *group_sizes,
  T *scratchpad,
  std::int64_t scratchpad_size,
  const std::vector<cl::sycl::event> &events = {})
}
Function supports the following precisions and devices.
T
Devices supported
float
Host, CPU, and GPU
double
Host, CPU, and GPU
Input Parameters
queue
Device queue where calculations will be performed.
m
Array of
group_count
 parameters m
g
 as previously supplied to geqrf_batch (Group Version).
n
Array of
group_count
 parameters n
g
 as previously supplied to geqrf_batch (Group Version).
k
Array of
group_count
 parameters
k
g
 as previously supplied to geqrf_batch (Group Version). The number of elementary reflectors whose product defines the matrices
Q
i
 (0 ≤
k
g
 ≤
n
g
) .
a
Array resulting after a call to
geqrf_batch (Group Version) <geqrf_batch-group-version
.
lda
Array of leading dimension of
A
i
 as previously supplied to geqrf_batch (Group Version).
tau
Array resulting after a call to geqrf_batch (Group Version).
group_count
Specifies the number of groups of parameters. Must be at least 0.
group_sizes
Array of group_count integers. Array element with index
g
 specifies the number of problems to solve for each of the groups of parameters
g
. So the total number of problems to solve,
batch_size
, is a sum of all parameter group sizes.
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 then the value returned by orgqr_batch_scratchpad_size (Group Version).
events
List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
a
Matrices pointed to by array
a
 are overwritten by
n
g
 leading columns of the
m
g
-by-
m
g
 orthogonal matrices
Q
i
, where
g
 is an index of group of parameters corresponding to
Q
i
.
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 then value returned by the detail() method of the exception object.
Return Values
Output event to wait on to ensure computation is complete.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.