Intel® oneAPI Math Kernel Library (oneMKL) - Data Parallel C++ Developer Reference

Developer Reference

Contents

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:
LaTex Math image.
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 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:
examples/dpcpp/blas/source/axpy.cpp

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 scalar
alpha
.
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.

Product and Performance Information

1

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