gels_batch (USM Strided Version)

oneMKL - Data Parallel C++ Developer Reference

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ID 772045

Date 3/31/2021

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gels_batch (USM Strided Version)

Finds the least squares solutions for a batch of overdetermined linear systems. This routine belongs to the oneapi::mkl::lapack namespace.

Description
API

Description

Finds the least squares solutions for a batch of overdetermined linear systems.

API

Syntax

namespace oneapi::mkl::lapack {
  sycl::event gels_batch(sycl::queue &queue,
  mkl::transpose trans,
  std::int64_t m,
  std::int64_t n,
  std::int64_t nrhs,
  T *a,
  std::int64_t lda,
  std::int64_t stride_a,
  T *b,
  std::int64_t ldb,
  std::int64_t stride_b,
  std::int64_t batch_size,
  T *scratchpad,
  std::int64_t scratchpad_size,
  const std::vector<sycl::event> &events = {})
}

This function supports the following precisions and devices:

T	Devices supported
`float`	GPU
`double`	GPU
`std::complex<float>`	GPU
`std::complex<double>`	GPU

Input Parameters

queue: Device queue where calculations will be performed.
trans: Operation assumed to be done on input matrices A_i. Only trans = mkl::transpose::nontrans case is currently supported.
m: The number of rows of the matrices A_i and B_i
n: The number of columns of the matrices A_i
nrhs: The number of right-hand sides: the number of columns in B_i
a: Contains batch_size m-by-n matrices A_i
lda: The leading dimension of A_i
stride_a: The stride between the beginnings of matrices A_i inside the batch array a
b: Contains the matrices B_i of right hand side vectors
ldb: The leading dimensions of B_i
stride_b: The stride between the beginnings of matrices B_i inside the batch array b.
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 type T. Size should not be less than the value returned by stride version of gels_batch_scratchpad_size (Strided Version) function.
events: List of events to wait for before starting computation. Defaults to empty list.

Output Parameters

a: Overwritten by the factorization data as follows: contains triangular matrix R obtained on the basis of A_i used in least squares computation
b: Overwritten by least squares solutions of the batch of problems

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. If `info` is zero, then `A`_i does not have full rank, and the solve could not be completed. The indexes of such matrices in the batch can be obtained with the `ids()` method of the exception object. You can obtain the indexes of the first zero diagonal elements in these matrices using the `infos()` method of the exception object.

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.

If info is zero, then A_i does not have full rank, and the solve could not be completed. The indexes of such matrices in the batch can be obtained with the ids() method of the exception object. You can obtain the indexes of the first zero diagonal elements in these matrices using the infos() method of the exception object.

Return Values

Output event to wait on to ensure computation is complete.

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oneMKL - Data Parallel C++ Developer Reference

gels_batch (USM Strided Version)

Description

API