trtrs
Solves a system of linear equations with a triangular 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 with a triangular matrix A
, with multiple right-hand
sides stored in B
:A*X = B | if transa =transpose::nontrans , | |
AT*X = B | if transa =transpose::trans , | |
A H *X = B | if transa =transpose::conjtrans (for complex matrices only). |
API
Syntax
namespace oneapi::mkl::lapack {
void trtrs(cl::sycl::queue &queue,
mkl::uplo uplo,
mkl::transpose trans,
mkl::diag diag,
std::int64_t n,
std::int64_t nrhs,
cl::sycl::buffer<T> &a,
std::int64_t lda,
cl::sycl::buffer<T> &b,
std::int64_t ldb,
cl::sycl::buffer<T> &scratchpad,
std::int64_t scratchpad_size)
}
trtrs
supports the following precisions and devices.T | Devices supported |
---|---|
float | Host, CPU, and GPU |
double | Host, CPU, and GPU |
std::complex<float> | Host, CPU, and GPU |
std::complex<double> | Host, CPU, and GPU |
Input Parameters
- queue
- Device queue where calculations will be performed.
- uplo
- Indicates whetherAis upper or lower triangular:If uplo =uplo::upper, thenAis upper triangular.If uplo =uplo::lower, thenAis lower triangular.
- trans
- If transa =transpose::nontrans, thenA*X=Bis solved forX.If transa =transpose::trans, thenAT*X=Bis solved forX.If transa =transpose::conjtrans, thenAH*X=Bis solved forX.
- diag
- If diag =diag::nonunit, thenAis not a unit triangular matrix.If diag =diag::unit, thenAis unit triangular: diagonal elements ofAare assumed to be 1 and not referenced in the array a.
- n
- The order ofA; the number of rows inB; n≥ 0.
- nrhs
- The number of right-hand sides; nrhs≥ 0.
- a
- Array containing the matrixA.The second dimension of a must be at leastmax(1,n).
- lda
- The leading dimension ofa; lda≥ max(1, n).
- b
- Array containing the matrixBwhose columns are the right-hand sides for the systems of equations.The second dimension of b at leastmax(1,nrhs).
- ldb
- The leading dimension of b; ldb≥ max(1, n).
- 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 typeT. Size should not be less than the value returned by the trtrs_scratchpad_size function.
Output Parameters
- b
- 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 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
- info
- Buffer containing error information.Ifinfo= 0, the execution is successful.Ifinfo= -i, thei-th parameter had an illegal value.
Known Limitations
GPU support for this function does not include error reporting through the
info
parameter.