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

Developer Reference

Contents

potri (USM Version)

Computes the inverse of a symmetric (Hermitian) positive-definite matrix using the Cholesky factorization. This routine belongs to the
oneapi::mkl::lapack
 namespace.

Description

The routine computes the inverse
inv(A)
 of a symmetric positive definite or, for complex flavors, Hermitian positive-definite matrix
A
. Before calling this routine, call potrf (USM Version) to factorize
A
.

API

Syntax
namespace oneapi::mkl::lapack {
  cl::sycl::event potri(cl::sycl::queue &queue,
  mkl::uplo uplo,
  std::int64_t n,
  T* a,
  std::int64_t lda,
  T *scratchpad,
  std::int64_t scratchpad_size,
  const std::vector<cl::sycl::event> &events = {})
}
potri
 (USM version) supports the following precisions and devices:
T
Devices Supported
float
Host, CPU, GPU
double
Host, CPU, GPU
std::complex<float>
Host, CPU, GPU
std::complex<double>
Host, CPU, GPU
Input Parameters
queue
Device queue where calculations will be performed.
uplo
Indicates how the input matrix A has been factored:
If
uplo = mkl::uplo::upper
, the upper triangle of
A
 is stored.
If
uplo = mkl::uplo::lower
, the lower triangle of
A
 is stored.
n
Specifies the order of the matrix
A
 (
0≤n
).
a
Contains the factorization of the matrix
A
, as returned by potrf (USM Version). The second dimension of
a
 must be at least
max(1, n)
.
lda
The leading dimension of
a
.
scratchpad
Pointer to scratchpad memory to be used by the 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 the potri_scratchpad_size function.
events
List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
a
Overwritten by the upper or lower triangle of the inverse of
A
. Specified by uplo.
Exceptions
Exception
Description
mkl::lapack::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 = -i
, the
i
-th parameter had an illegal value.
If
info = i
, the
i
-th diagonal element of the Cholesky factor (and therefore the factor itself) is zero, and the inversion could not be completed.
If
info
 is equal to the value passed as scratchpad size, and detail() returns non zero, then the passed scratchpad has an insufficient size, and the required size should not be less than the 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.