getrs#
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 |
|---|---|
|
if |
|
if |
|
if |
Before calling this routine, you must call getrf to compute the LU factorization of A.
API#
Syntax#
namespace oneapi::mkl::lapack {
void getrs(sycl::queue &queue,
mkl::transpose trans,
int64_t n,
int64_t nrhs,
sycl::buffer<T> &a,
int64_t lda,
sycl::buffer<T> &ipiv,
sycl::buffer<T> &b,
int64_t ldb,
sycl::buffer<T> &scratchpad,
int64_t scratchpad_size)
}
getrs supports the following precisions and devices:
T |
Devices supported |
|---|---|
|
CPU and GPU |
|
CPU and GPU |
|
CPU and GPU |
|
CPU and GPU |
Input Parameters#
- queue
Device queue where calculations will be performed.
- trans
Indicates the form of the equations:
If
trans=mkl::transpose::nontrans, thenA*X = Bis solved forX.If
trans=mkl::transpose::trans, thenAT*X = Bis solved forX.If
trans=mkl::transpose::conjtrans, thenAH*X = Bis solved forX.- n
The order of the matrix
Aand the number of rows in matrixB(0 ≤ n).- nrhs
The number of right-hand sides (
0 ≤ nrhs).- a
Buffer holding the array containing the factorization of the matrix
A, as returned by getrf. The size of the buffer must be at least`lda*n.- lda
The leading dimension of a.
- ipiv
Buffer holding array of size at least
max(1, n)as returned by getrf.- b
The array b contains the matrix
Bwhose columns are the right-hand sides for the systems of equations. The size of b must be at leastldb*nrhs.- ldb
The leading dimension of b.
- scratchpad
Buffer holding 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 getrs_scratchpad_size function.
Output Parameters#
- b
The buffer b is overwritten by the solution matrix
X.
Exceptions#
Exception |
Description |
|---|---|
|
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 If If |