axpy

oneMKL - Data Parallel C++ Developer Reference

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ID 772045

Date 3/31/2025

Version

Public

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axpy

Computes a vector-scalar product and adds the result to a vector.

Description

The axpy routines compute a scalar-vector product and add the result to a vector. The operation is defined as:

where:

x and y are vectors of n elements
alpha is a scalar

axpy supports the following precisions:

T
`sycl::half`
`oneapi::mkl::bfloat16`
`float`
`double`
`std::complex<float>`
`std::complex<double>`

axpy (Buffer Version)

Syntax

namespace oneapi::mkl::blas::column_major {
    void axpy(sycl::queue &queue,
              std::int64_t n,
              T alpha,
              sycl::buffer<T,1> &x,
              std::int64_t incx,
              sycl::buffer<T,1> &y,
              std::int64_t incy)
}

namespace oneapi::mkl::blas::row_major {
    void axpy(sycl::queue &queue,
              std::int64_t n,
              T alpha,
              sycl::buffer<T,1> &x,
              std::int64_t incx,
              sycl::buffer<T,1> &y,
              std::int64_t incy)
}

Input Parameters

queue: The queue where the routine should be executed.
n: Number of elements in vector x.
alpha: Specifies scalar alpha.
x: Buffer holding input vector x. Size of the buffer must be at least (1 + (n – 1)*abs(incx)). See Matrix Storage for more details.
incx: Stride of vector x.
y: Buffer holding input vector y. Size of the buffer must be at least (1 + (n – 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 axpy can be found in the oneMKL installation directory, under:

share/doc/mkl/examples/sycl/blas/source/axpy.cpp

axpy (USM Version)

Syntax

namespace oneapi::mkl::blas::column_major {
    sycl::event axpy(sycl::queue &queue,
                     std::int64_t n,
                     oneapi::mkl::value_or_pointer<T> alpha,
                     const T *x,
                     std::int64_t incx,
                     T *y,
                     std::int64_t incy,
                     const std::vector<sycl::event> &dependencies = {})
}

namespace oneapi::mkl::blas::row_major {
    sycl::event axpy(sycl::queue &queue,
                     std::int64_t n,
                     oneapi::mkl::value_or_pointer<T> alpha,
                     const T *x,
                     std::int64_t incx,
                     T *y,
                     std::int64_t incy,
                     const std::vector<sycl::event> &dependencies = {})
}

Input Parameters

queue: The queue where the routine should be executed.
n: Number of elements in vector x.
alpha: Specifies the scalar alpha. See Scalar Arguments for more information on the value_or_pointer data type.
x: Pointer to input vector x. Size of the array holding vector x must be at least (1 + (n – 1)*abs(incx)). See Matrix Storage for more details.
incx: Stride of vector x.
y: Pointer to input vector y. Size of the array holding vector y must be at least (1 + (n – 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.

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oneMKL - Data Parallel C++ Developer Reference

axpy

Description

axpy (Buffer Version)

Examples

axpy (USM Version)