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gesv (USM Version)
Computes the solution to the system of linear equations with a square coefficient matrix and multiple right-hand sides. This routine belongs to the oneapi::mkl::lapack namespace.
Description
The routine solves for X the system of linear equations A*X = B, where A is an n-by-n matrix, the columns of matrix B are individual right-hand sides, and the columns of X are the corresponding solutions.
The LU decomposition with partial pivoting and row interchanges is used to factor A as A = P*L*U, where P is a permutation matrix, L is unit lower triangular, and U is upper triangular. The factored form of A is then used to solve the system of equations A*X = B.
API
Syntax
namespace oneapi::mkl::lapack {
sycl::event gesv(sycl::queue &queue,
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<sycl::event> &events = {})
}
gesv (USM version) supports the following precisions and devices:
T |
Devices supported |
|---|---|
float |
CPU, GPU |
double |
CPU, GPU |
std::complex<float> |
CPU, GPU |
std::complex<double> |
CPU, GPU |
Input Parameters
- queue
-
Device queue where calculations will be performed.
- n
-
The order of the matrix A; (0 ≤ n).
- nrhs
-
The number of right-hand sides (0 ≤ nrhs).
- a
-
Pointer to the n-by-n coefficient matrix A.
- lda
-
The leading dimension of a.
- b
-
Pointer to the n-by-nrhs matrix of right hand side matrix B
- 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 type T. Size should not be less than the value returned by the gesv_scratchpad_size function.
- events
-
List of events to wait for before starting computation. Defaults to empty list.
Output Parameters
- a
-
Overwritten by the factors L and U from the factorization of A = P*L*U; the unit diagonal elements of L are not stored.
- b
-
The buffer b is overwritten by the solution matrix X.
- ipiv
-
Array, size at least max(1, n). The ipiv array, as returned by getrf (USM Version).
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.