axpy_batch¶

The axpy_batch routines are batched versions of axpy, performing multiple axpy operations in a single call. Each axpy operation adds a scalar-vector product to a vector.

axpy_batch supports the following precisions.

T

float

double

std::complex<float>

std::complex<double>

axpy_batch (Buffer Version)¶

Description

The buffer version of axpy_batch supports only the strided API.

The strided API operation is defined as

for i = 0 … batch_size – 1
   X and Y are vectors at offset i * stridex, i * stridey in x and y
   Y := alpha * X + Y
end for

where:

alpha is scalar

X and Y are vectors.

Strided API

Syntax

void onemkl::blas::axpy_batch(sycl::queue &queue, std::int64_t n, T alpha, sycl::buffer<T, 1> &x, std::int64_t incx, std::int64_t stridex, sycl::buffer<T, 1> &y, std::int64_t incy, std::int64_t stridey, std::int64_t batch_size)¶

Input Parameters

queue: The queue where the routine should be executed.
n: Number of elements in X and Y.
alpha: Specifies the scalar alpha.
x: Buffer holding input vectors X with size stridex*batch_size.
incx: Stride of vector X.
stridex: Stride between different X vectors.
y: Buffer holding input/output vectors Y with size stridey*batch_size.
incy: Stride of vector Y.
stridey: Stride between different Y vectors.
batch_size: Specifies the number of axpy operations to perform.

Output Parameters

y: Output buffer, overwritten by batch_size axpy operations of the form alpha*X + Y.

axpy_batch (USM Version)¶

Description

The USM version of axpy_batch supports the group API and strided API.

The group API operation is defined as

idx = 0
for i = 0 … group_count – 1
    for j = 0 … group_size – 1
        X and Y are vectors in x[idx] and y[idx]
        Y := alpha[i] * X + Y
        idx := idx + 1
    end for
end for

The strided API operation is defined as

for i = 0 … batch_size – 1
   X and Y are vectors at offset i * stridex, i * stridey in x and y
   Y := alpha * X + Y
end for

where:

alpha is scalar

X and Y are vectors.

For group API, x and y arrays contain the pointers for all the input vectors. The total number of vectors in x and y are given by:

total_batch_count = sum of all of the group_size entries

For strided API, x and y arrays contain all the input vectors. The total number of vectors in x and y are given by the batch_size parameter.

Group API

Syntax

sycl::event onemkl::blas::axpy_batch(sycl::queue &queue, std::int64_t *n, T *alpha, const T **x, std::int64_t *incx, T **y, std::int64_t *incy, std::int64_t group_count, std::int64_t *group_size, const sycl::vector_class<sycl::event> &dependencies = {})¶

Input Parameters

queue: The queue where the routine should be executed.
n: Array of group_count integers. n[i] specifies the number of elements in vectors X and Y for every vector in group i.
alpha: Array of group_count scalar elements. alpha[i] specifies the scaling factor for vector X in group i.
x: Array of pointers to input vectors X with size total_batch_count. The size of array allocated for the X vector of the group i must be at least (1 + (n[i] – 1)*abs(incx[i])). See Matrix and Vector Storage for more details.
incx: Array of group_count integers. incx[i] specifies the stride of vector X in group i.
y: Array of pointers to input/output vectors Y with size total_batch_count. The size of array allocated for the Y vector of the group i must be at least (1 + (n[i] – 1)*abs(incy[i])). See Matrix and Vector Storage for more details.
incy: Array of group_count integers. incy[i] specifies the stride of vector Y in group i.
group_count: Number of groups. Must be at least 0.
group_size: Array of group_count integers. group_size[i] specifies the number of axpy operations in group i. Each element in group_size must be at least 0.
dependencies: List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters

y: Array of pointers holding the Y vectors, overwritten by total_batch_count axpy operations of the form alpha*X + Y.

Return Values

Output event to wait on to ensure computation is complete.

Strided API

Syntax

sycl::event onemkl::blas::axpy_batch(sycl::queue &queue, std::int64_t n, T alpha, const T *x, std::int64_t incx, std::int64_t stridex, T *y, std::int64_t incy, std::int64_t stridey, std::int64_t batch_size, const sycl::vector_class<sycl::event> &dependencies = {})¶

Input Parameters

queue: The queue where the routine should be executed.
n: Number of elements in X and Y.
alpha: Specifies the scalar alpha.
x: Pointer to input vectors X with size stridex*batch_size.
incx: Stride of vector X.
stridex: Stride between different X vectors.
y: Pointer to input/output vectors Y with size stridey*batch_size.
incy: Stride of vector Y.
stridey: Stride between different Y vectors.
batch_size: Specifies the number of axpy operations to perform.
dependencies: List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters

y: Output vectors, overwritten by batch_size axpy operations of the form alpha*X + Y.

Return Values

Output event to wait on to ensure computation is complete.

Parent topic:BLAS-like Extensions