Intel® oneAPI Math Kernel Library (oneMKL) - Data Parallel C++ Developer Reference
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potrf_batch (Buffer Strided Version)
Computes the Cholesky factorizations of a batch of symmetric (or Hermitian, for complex data) positive-definite matrices. This routine belongs to the oneapi::mkl::lapack namespace.
Description
The routine forms the Cholesky factorizations of a symmetric positive-definite or, for complex data, Hermitian positive-definite matrices Ai, iϵ{1...batch_size}:
Ai = UiT * Ui for real data, Ai = UiH * Ui for complex data. if uplo = mkl::uplo::upper,
Ai = LiT * Li for real data, Ai = LiH * Li for complex data if uplo = mkl::uplo::lower
Where Li is a lower triangular matrix and Ui is an upper triangular matrix.
API
Syntax
namespace oneapi::mkl::lapack {
void potrf_batch(sycl::queue &queue,
mkl::uplo uplo,
std::int64_t n,
sycl::buffer<T> &a,
std::int64_t lda,
std::int64_t stride_a,
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.
- uplo
-
Indicates whether the upper or lower triangular part of Ai is stored and how Ai is factored:
If uplo = mkl::uplo::upper, the array a stores the upper triangular parts of the matrices Ai.
If uplo = mkl::uplo::lower, the array a stores the lower triangular parts of the matrices Ai.
- n
-
Specifies the order of the matrices Ai, (0 ≤ n).
- a
-
Array containing a batch of input matrices Ai, each of Ai being of size lda*n and holding either uppoer or lower triangular parts of the matrices Ai (see uplo).
- lda
-
The leading dimension of Ai.
- stride_a
-
The stride between the beginnings of matrices Ai inside the batch.
- 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 then the value returned by potrf_batch_scratchpad_size (Strided Version).
Output Parameters
- a
-
The batch array a is overwritten by the Cholesky factor Ui or Li, as specified by uplo .
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 the diagonal element of some of Ui is zero, 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 Ui matrices using the infos() method of the exception object. |