Contents

# axpby

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

## Description

The
axpby
routines compute two scalar-vector products and add them:
where:
• x
and
y
are vectors of
n
elements
• 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 vectors
x
and
y
.
alpha
Specifies the 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 between two consecutive elements of vector
x
.
beta
Specifies the scalar
beta
.
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 between two consecutive elements of vector
y
.
Output Parameters
y
Buffer holding 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,
T beta,
T *y,
std::int64_t incy,
const std::vector<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,
T beta,
T *y,
std::int64_t incy,
const std::vector<event> &dependencies = {});
}``````
Input Parameters
queue
The queue where the routine should be executed.
n
Number of elements in vectors
x
and
y
.
alpha
Specifies the scalar
alpha
.
x
Pointer to the input vector
x
. Size of the array must be at least 1 + (
n
- 1)*abs(
incx
)). See Matrix Storage for more details.
incx
Stride between two consecutive elements of vector
x
.
beta
Specifies the scalar
beta
.
y
Pointer to the input vector
y
. Size of the array must be at least 1 + (
n
- 1)*abs(
incy
)). See Matrix Storage for more details.
incy
Stride between two consecutive elements of vector
y
.
dependencies
List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.
Output Parameters
y
Array holding updated vector
y
.
Return Values
Output event to wait on to ensure computation is complete.

#### Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.