potrf_batch (USM 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
A
i
, i
ϵ{1...batch_size}
:- Ai=UiT*Uifor real data,Ai=UiH*Uifor complex data. ifuplo = mkl::uplo::upper,
- Ai=LiT*Lifor real data,Ai=LiH*Lifor complex data ifuplo = mkl::uplo::lower
Where
L
i
is a lower triangular matrix and
U
i
is an upper triangular matrix.API
Syntax
namespace oneapi::mkl::lapack {
cl::sycl::event potrf_batch(cl::sycl::queue &queue,
mkl::uplo uplo,
std::int64_t n,
T *a,
std::int64_t lda,
std::int64_t stride_a,
std::int64_t batch_size,
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 |
std::complex<float> | Host, CPU, and GPU |
std::complex<double> | Host, CPU, and GPU |
Input Parameters
- queue
- Device queue where calculations will be performed.
- uplo
- Indicates whether the upper or lower triangular part ofAiis stored and howAiis factored:If uplo = mkl::uplo::upper, the arrayastores the upper triangular parts of the matricesAi.If uplo = mkl::uplo::lower, the arrayastores the lower triangular parts of the matricesAi.
- n
- Specifies the order of the matricesAi, (0 ≤ n).
- a
- Array containing a batch of input matricesAi, each ofAibeing of sizelda*nand holding either uppoer or lower triangular parts of the matricesAi(see uplo).
- lda
- The leading dimension ofAi.
- stride_a
- The stride between the beginnings of matricesAiinside the batch.
- batch_size
- Specifies 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).
- events
- List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
- a
- The batch arrayais overwritten by the Cholesky factorUiorLi, 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 U i 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 U i matrices using the infos() method of the exception object. |
Return Values
Output event to wait on to ensure computation is complete.