gemv

oneMKL - Data Parallel C++ Developer Reference

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ID 772045

Date 11/07/2023

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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 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. Must not be zero.
beta: Scaling factor for vector y. If beta = 0, vector y does not need to be initialized before calling gemv.
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. Must not be zero.

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:

share/doc/mkl/examples/sycl/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,
                     oneapi::mkl::value_or_pointer<T> alpha,
                     const T *a,
                     std::int64_t lda,
                     const T *x,
                     std::int64_t incx,
                     oneapi::mkl::value_or_pointer<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,
                     oneapi::mkl::value_or_pointer<T> alpha,
                     const T *a,
                     std::int64_t lda,
                     const T *x,
                     std::int64_t incx,
                     oneapi::mkl::value_or_pointer<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. See Scalar Arguments for more information on the value_or_pointer data type.
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. Must not be zero.
beta: Scaling factor for vector y. If beta = 0, vector y does not need to be initialized before calling gemv. See Scalar Arguments for more information on the value_or_pointer data type.
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. Must not be zero.
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.

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oneMKL - Data Parallel C++ Developer Reference

gemv

Description

gemv (Buffer Version)

Examples

gemv (USM Version)