gemv¶
Computes a matrix-vector product using a general matrix.
Description¶
The gemv
routines compute a scalar-matrix-vector product and add the result to a scalar-vector product, with a general matrix. The operation is defined as
where:
op(
A
) is one of op(A
) =A
, or op(A
) =A
T, or op(A
) =A
H,alpha
andbeta
are scalars,A
is anm
-by-n
matrix, andx
,y
are vectors.
API¶
Syntax¶
namespace oneapi::mkl::blas::column_major {
void gemv(sycl::queue &queue,
onemkl::transpose trans,
std::int64_t m,
std::int64_t n,
T alpha,
sycl::buffer<T,1> &a,
std::int64_t lda,
sycl::buffer<T,1> &x,
std::int64_t incx,
T beta,
sycl::buffer<T,1> &y,
std::int64_t incy)
}
namespace oneapi::mkl::blas::row_major {
void gemv(sycl::queue &queue,
onemkl::transpose trans,
std::int64_t m,
std::int64_t n,
T alpha,
sycl::buffer<T,1> &a,
std::int64_t lda,
sycl::buffer<T,1> &x,
std::int64_t incx,
T beta,
sycl::buffer<T,1> &y,
std::int64_t incy)
}
gemv
supports the following precisions and devices.
T |
Devices Supported |
---|---|
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
Input Parameters¶
- exec_queue
The queue where the routine should be executed.
- trans
Specifies
op(A)
, the transposition operation applied toA
. See Data Types for more details.- m
Specifies the number of rows of the matrix
A
. The value ofm
must be at least zero.- n
Specifies the number of columns of the matrix
A
. The value ofn
must be at least zero.- alpha
Scaling factor for the matrix-vector product.
- a
The array holding input matrix
A
must have size at leastlda
*n
if column major layout is used, or at leastlda
*m
if row major layout is used.- lda
The leading dimension of matrix
A
. It must be positive and at least m if column major layout is used or at least n if row major layout is used.- x
Buffer holding input vector
x
. The lengthlen
of vectorx
isn
ifA
is not transposed, andm
ifA
is transposed. The buffer must be of size at least (1 + (len
- 1)*abs(incx
)). See Matrix Storage for more details.- incx
The stride of vector
x
.- beta
The scaling factor for vector
y
.- y
Buffer holding input/output vector
y
. The lengthlen
of vectory
ism
, ifA
is not transposed, andn
ifA
is transposed. The buffer must be of size at least (1 + (len
- 1)*abs(incy
)) wherelen
is this length. See Matrix Storage for more details.- incy
The stride of vector
y
.
Output Parameters¶
- y
The buffer holding updated vector
y
.
Examples¶
An example of how to use gemv
can be found in the oneMKL installation directory, under:
examples/dpcpp/blas/source/gemv.cpp