# axpby¶

Computes a vector-scalar product added to a scaled-vector.

Description

The axpby routines compute two scalar-vector product and add them:

$y \leftarrow beta * y + alpha * x$

where x and y are vectors of n elements and alpha and beta are scalars.

axpby supports the following precisions.

T

float

double

std::complex<float>

std::complex<double>

## axpby (Buffer Version)¶

Syntax

namespace oneapi::mkl::blas::column_major {
void axpby(sycl::queue &queue,
std::int64_t n,
T alpha,
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 axpby(sycl::queue &queue,
std::int64_t n,
T alpha,
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.

n

Number of elements in vector x and y.

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 between two consecutive elements of the x vector.

beta

Specifies the scalar beta.

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 between two consecutive elements of the y vector.

Output Parameters

y

Buffer holding the updated vector y.

## axpby (USM Version)¶

Syntax

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

namespace oneapi::mkl::blas::row_major {
sycl::event axpby(sycl::queue &queue,
std::int64_t n,
T alpha,
const T *x, std::int64_t incx,
const 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.

n

Number of elements in vector x and y.

alpha

Specifies the scalar alpha.

beta

Specifies the scalar beta.

x

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

incx

Stride between consecutive elements of the x vector.

y

Pointer to the input vector y. The allocated memory must be of size at least (1 + (n – 1)*abs(incy)). See Matrix Storage for more details.

incy

Stride between consecutive elements of the y vector.

dependencies

List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters

y

Array holding the updated vector y.

Return Values

Output event to wait on to ensure computation is complete.

Parent topic: BLAS-like Extensions