potrf#
Computes the Cholesky factorization of a symmetric (Hermitian) positive-definite matrix.
Description
potrf
supports the following precisions.
T
float
double
std::complex<float>
std::complex<double>
The routine forms the Cholesky factorization of a symmetric positive-definite or, for complex data, Hermitian positive-definite matrix \(A\):
\(A\) = \(U^{T}U\) for real data, \(A = U^{H}U\) for complex data
if upper_lower=
oneapi::mkl::uplo::upper
\(A\) = \(LL^{T}\) for real data, \(A = LL^{H}\) for complex data
if upper_lower=
oneapi::mkl::uplo::lower
where \(L\) is a lower triangular matrix and \(U\) is upper triangular.
potrf (Buffer Version)#
Syntax
namespace oneapi::mkl::lapack {
void potrf(sycl::queue &queue, oneapi::mkl::uplo upper_lower, std::int64_t n, sycl::buffer<T,1> &a, std::int64_t lda, sycl::buffer<T,1> &scratchpad, std::int64_t scratchpad_size)
}
Input Parameters
- queue
The queue where the routine should be executed.
- upper_lower
Indicates whether the upper or lower triangular part of \(A\) is stored and how \(A\) is factored:
If upper_lower=
oneapi::mkl::uplo::upper
, the arraya
stores the upper triangular part of the matrix \(A\), and the strictly lower triangular part of the matrix is not referenced.If upper_lower=
oneapi::mkl::uplo::lower
, the arraya
stores the lower triangular part of the matrix \(A\), and the strictly upper triangular part of the matrix is not referenced.- n
Specifies the order of the matrix \(A\) (\(0 \le n\)).
- a
Buffer holding input matrix \(A\). The buffer
a
contains either the upper or the lower triangular part of the matrix \(A\) (see upper_lower). The second dimension ofa
must be at least \(\max(1, n)\).- lda
The leading dimension of
a
.- 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 potrf_scratchpad_size function.
Output Parameters
- a
The buffer
a
is overwritten by the Cholesky factor \(U\) or \(L\), as specified byupper_lower
.- scratchpad
Buffer holding scratchpad memory to be used by routine for storing intermediate results.
potrf (USM Version)#
Syntax
namespace oneapi::mkl::lapack {
sycl::event potrf(sycl::queue &queue, oneapi::mkl::uplo upper_lower, std::int64_t n, T *a, std::int64_t lda, T *scratchpad, std::int64_t scratchpad_size, const std::vector<sycl::event> &events = {})
}
Input Parameters
- queue
The queue where the routine should be executed.
- upper_lower
Indicates whether the upper or lower triangular part of \(A\) is stored and how \(A\) is factored:
If upper_lower=
oneapi::mkl::uplo::upper
, the arraya
stores the upper triangular part of the matrix \(A\), and the strictly lower triangular part of the matrix is not referenced.If upper_lower=
oneapi::mkl::uplo::lower
, the arraya
stores the lower triangular part of the matrix \(A\), and the strictly upper triangular part of the matrix is not referenced.- n
Specifies the order of the matrix \(A\) (\(0 \le n\)).
- a
Pointer to input matrix \(A\). The array
a
contains either the upper or the lower triangular part of the matrix \(A\) (see upper_lower). The second dimension ofa
must be at least \(\max(1, n)\).- lda
The leading dimension of
a
.- 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 potrf_scratchpad_size function.- events
List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
- a
The memory pointer to by pointer
a
is overwritten by the Cholesky factor \(U\) or \(L\), as specified byupper_lower
.- scratchpad
Pointer to scratchpad memory to be used by routine for storing intermediate results.
Return Values
Output event to wait on to ensure computation is complete.
Parent topic: LAPACK Linear Equation Routines