getrs (USM Version)
Solves a system of linear equations with an LU-factored square
coefficient matrix, with multiple right-hand sides. This routine belongs
to the
oneapi::mkl::lapack
namespace.Description
The routine solves for
X
the following systems of linear
equations:Equation | Condition |
---|---|
A*X = B | if trans =mkl::transpose::nontrans |
AT*X = B | if trans =mkl::transpose::trans |
AH*X = B | if trans =mkl::transpose::conjtrans |
Before calling this routine, you must call the getrf (USM Version) function to compute the
LU
factorization of A
.API
Syntax
namespace oneapi::mkl::lapack {
cl::sycl::event getrs(cl::sycl::queue &queue,
mkl::transpose trans,
std::int64_t n,
std::int64_t nrhs,
T *a,
std::int64_t lda,
std::int64_t *ipiv,
T *b,
std::int64_t ldb,
T *scratchpad,
std::int64_t scratchpad_size,
const std::vector<cl::sycl::event> &events = {})
}
getrs
(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.
- trans
- Indicates the form of the equations:Iftrans=mkl::transpose::nontrans, thenA*X = Bis solved forX.Iftrans=mkl::transpose::trans, thenAT*X = Bis solved forX.Iftrans=mkl::transpose::conjtrans, thenAH*X = Bis solved forX.
- n
- The order of the matrixAand the number of rows in matrixB(0≤n).
- nrhs
- The number of right-hand sides (0≤nrhs).
- a
- Pointer to the array containing the factorization of the matrixA, as returned by getrf (USM Version). The second dimension of a must be at leastmax(1, n).
- lda
- The leading dimension of a.
- ipiv
- Array, size at leastmax(1, n). The ipiv array, as returned by getrf (USM Version).
- b
- The array b contains the matrixBwhose columns are the right-hand sides for the systems of equations. The second dimension of b must be at leastmax(1,nrhs).
- ldb
- The leading dimension of b.
- 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 typeT. Size should not be less than the value returned by the getrs_scratchpad_size function.
- events
- List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
- b
- The buffer b is overwritten by the solution matrixX.
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 U is zero, and the solve 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.