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:

\[y \leftarrow alpha*op(A)*x + beta*y\]

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 an m-by-n matrix, and x, y are vectors.

gemv supports the following precisions.

T

float

double

std::complex<float>

std::complex<double>

T
`float`
`double`
`std::complex<float>`
`std::complex<double>`

gemv (Buffer Version)#

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)
}

Input Parameters

queue: The queue where the routine should be executed.
trans: Specifies op(A), the transposition operation applied to A.
m: Specifies the number of rows of the matrix A. The value of m must be at least zero.
n: Specifies the number of columns of the matrix A. The value of n must be at least zero.
alpha: Scaling factor for the matrix-vector product.
a: The buffer holding the input matrix A. Must have a size of 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. 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 length len of vector y is m, if A is not transposed, and n if A is transposed. The buffer must be of size at least (1 + (len - 1)*abs(incy)) where len is this length. See Matrix Storage for more details.
incy: The stride of vector y.

Output Parameters

y: The buffer holding updated vector y.

gemv (USM Version)#

Syntax

namespace oneapi::mkl::blas::column_major {
    sycl::event gemv(sycl::queue &queue,
                     onemkl::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,
                     onemkl::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 A. See oneMKL Defined Datatypes for more details.
m: Specifies the number of rows of the matrix A. The value of m must be at least zero.
n: Specifies the number of columns of the matrix A. The value of n must be at least zero.
alpha: Scaling factor for the matrix-vector product.
a: Pointer to the input matrix A. Must have a size of 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: 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. The array holding vector x 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: 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. The array holding input/output vector y must be of size at least (1 + (len - 1)*abs(incy)) where len is this length. See Matrix Storage for more details.
incy: The 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: The pointer to updated vector y.

Return Values

Output event to wait on to ensure computation is complete.

Parent topic: BLAS Level 2 Routines

gemv

Contents

gemv#

gemv (Buffer Version)#

gemv (USM Version)#