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Visible to Intel only — GUID: GUID-25DAA8BE-6377-417F-B7ED-80BE48A6D01A
Visible to Intel only — GUID: GUID-25DAA8BE-6377-417F-B7ED-80BE48A6D01A
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 |
|---|---|
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 getrf to compute the LU factorization of A.
API
Syntax
namespace oneapi::mkl::lapack { void getrs(sycl::queue &queue, mkl::transpose trans, std::int64_t n, std::int64_t nrhs, sycl::buffer<T> &a, std::int64_t lda, sycl::buffer<T> &ipiv, sycl::buffer<T> &b, std::int64_t ldb, sycl::buffer<T> &scratchpad, std::int64_t scratchpad_size) }
getrs 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.
- trans
-
Indicates the form of the equations:
If trans=mkl::transpose::nontrans, then A*X = B is solved for X.
If trans=mkl::transpose::trans, then AT*X = B is solved for X.
If trans=mkl::transpose::conjtrans, then AH*X = B is solved for X.
- n
-
The order of the matrix A and the number of rows in matrix B(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 second dimension of a must be at least max(1, 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 B whose columns are the right-hand sides for the systems of equations. The second dimension of b must be at least max(1,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 |
|---|---|
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. |