Intel® oneAPI Math Kernel Library (oneMKL) - Data Parallel C++ Developer Reference
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Visible to Intel only — GUID: GUID-D5E815C3-80A8-4BD2-A16E-7339FCDCAFD4
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) = AT, or op(A) = AH
alpha and beta are scalars
A is m x n matrix
x and y are vectors
gemv supports the following precisions:
T |
|---|
float |
double |
std::complex<float> |
std::complex<double> |
gemv (Buffer Version)
Syntax
namespace oneapi::mkl::blas::column_major {
void gemv(sycl::queue &queue,
oneapi::mkl::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,
oneapi::mkl::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)
}
Input Parameters
- queue
-
The queue where the routine should be executed.
- trans
-
Specifies op(A), the transposition operation applied to matrix A. See Data Types for more details.
- m
-
Number of rows of matrix A. Must be at least zero.
- n
-
Number of columns of matrix A. Must be at least zero.
- alpha
-
Scaling factor for the matrix-vector product.
- a
-
Buffer holding input matrix A. Size of the buffer must be at least lda * n if column major layout is used, or at least lda * m if row major layout is used. See Matrix Storage for more details.
- lda
-
Leading dimension of matrix A. 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 length len of vector x is n if A is not transposed, and m if A is transposed. Size of the buffer must be at least (1 + (len - 1)*abs(incx)). See Matrix Storage for more details.
- incx
-
Stride of vector x.
- beta
-
The scaling factor for vector y.
- y
-
Buffer holding input/output vector y. The length len of vector y is m, if A is not transposed, and n if A is transposed. Size of the buffer must be at least (1 + (len - 1)*abs(incy)). See Matrix Storage for more details.
- incy
-
Stride of vector y.
Output Parameters
- y
-
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
gemv (USM Version)
Syntax
namespace oneapi::mkl::blas::column_major {
sycl::event gemv(sycl::queue &queue,
oneapi::mkl::transpose trans,
std::int64_t m,
std::int64_t n,
T alpha,
const T *a,
std::int64_t lda,
const T *x,
std::int64_t incx,
T beta,
T *y,
std::int64_t incy,
const std::vector<sycl::event> &dependencies = {})
}
namespace oneapi::mkl::blas::row_major {
sycl::event gemv(sycl::queue &queue,
oneapi::mkl::transpose trans,
std::int64_t m,
std::int64_t n,
T alpha,
const T *a,
std::int64_t lda,
const T *x,
std::int64_t incx,
T beta,
T *y,
std::int64_t incy,
const std::vector<sycl::event> &dependencies = {})
}
Input Parameters
- queue
-
The queue where the routine should be executed.
- trans
-
Specifies op(A), the transposition operation applied to matrix A. See Data Types for more details.
- m
-
Number of rows of matrix A. Must be at least zero.
- n
-
Number of columns of matrix A. Must be at least zero.
- alpha
-
Scaling factor for the matrix-vector product.
- a
-
Pointer to input matrix A. Size of the array must be at least lda * n if column major layout is used, or at least lda * m if row major layout is used.
- lda
-
Leading dimension of matrix A. Must be positive and at least m if column major layout is used or at least n if row major layout is used.
- x
-
Pointer to the input vector x. The length len of vector x is n if A is not transposed, and m if A is transposed. Size of the array holding vector x must be at least (1 + (len - 1)*abs(incx)). See Matrix Storage for more details.
- incx
-
Stride of vector x.
- beta
-
Scaling factor for vector y.
- y
-
Pointer to input/output vector y. The length len of vector y is m, if A is not transposed, and n if A is transposed. Size of the array holding input/output vector y must be at least (1 + (len - 1)*abs(incy)). See Matrix Storage for more details.
- incy
-
Stride of vector y.
- dependencies
-
List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.
Output Parameters
- y
-
Pointer to updated vector y.
Return Values
Output event to wait on to ensure computation is complete.