# 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:

$y \leftarrow alpha * x + y$

where:

x and y are vectors of n elements,

alpha is a scalar.

axpy supports the following precisions.

T

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 the scalar alpha.

x

Buffer holding input vector x. The buffer must be of size at least (1 + (n – 1)*abs(incx)). See Matrix Storage for more details.

incx

Stride of vector x.

y

Buffer holding input vector y. The buffer must be of size at least (1 + (n – 1)*abs(incy)). See Matrix Storage for more details.

incy

Stride of vector y.

Output Parameters

y

Buffer holding the updated vector y.

## axpy (USM Version)¶

Syntax

namespace oneapi::mkl::blas::column_major {
sycl::event axpy(sycl::queue &queue,
std::int64_t n,
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,
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.

x

Pointer to the input vector x. The array holding the vector x must be of size at least (1 + (n – 1)*abs(incx)). See Matrix Storage for more details.

incx

Stride of vector x.

y

Pointer to the input vector y. The array holding the vector y must be of size 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 the updated vector y.

Return Values

Output event to wait on to ensure computation is complete.

Parent topic: BLAS Level 1 Routines