potrf_batch (Group 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. ifuplog = mkl::uplo::upper,
- Ai=LiT*Lifor real data,Ai=LiH*Lifor complex data ifuplog = mkl::uplo::lower
Where
L
i
is a lower triangular matrix and
U
i
is an upper triangular matrix, g
is an index of
group of parameters corresponding to A
i
, and the total
number of problems to solve, batch_size
, is a sum of sizes for
all of the groups of parameters as provided by the group_sizes
array.API
Syntax
namespace oneapi::mkl::lapack {
sycl::event potrf_batch(sycl::queue &queue,
mkl::uplo *uplo,
std::int64_t *n,
T **a,
std::int64_t *lda,
std::int64_t group_count,
std::int64_t *group_sizes,
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 | 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
- Array ofgroup_countuplogparameters.Each of uplogindicates whether the upper or lower triangular parts of the input matrices are provided:If uplog=mkl::uplo::upper, input matrices from arrayabelonging to groupgstore the upper triangular parts.If uplog=mkl::uplo::lower, input matrices from arrayabelonging to groupgstore the lower triangular parts.
- n
- Array ofgroup_countparametersng.Eachngspecifies the order of the input matrices from arrayabelonging to groupg.
- a
- Array ofbatch_sizepointers to input matricesAi, each being of sizeldag*ng(gis an index of the group to whichAibelongs) and holding either upper or lower triangular part as specified by uplog.
- lda
- Array ofgroup_countparameters ldag.Each ldagspecifies the leading dimension of matrices fromabelonging to groupg.
- group_count
- Specifies the number of groups of parameters. Must be at least 0.
- group_sizes
- Array of group_count integers. Array element with indexgspecifies the number of problems to solve for each of the groups of parametersg. 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 potrf_batch_scratchpad_size (Group Version).
- events
- List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
- a
- The matrices pointed to by array a are overwritten by the Cholesky factorsUiorLi, as specified by uplogfrom the corresponding group of parameters.
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.