# hbmv#

Computes a matrix-vector product using a Hermitian band matrix.

Description

The hbmv routines compute a scalar-matrix-vector product and add the result to a scalar-vector product, with a Hermitian band matrix. The operation is defined as

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

where:

alpha and beta are scalars,

A is an n-by-n Hermitian band matrix, with k super-diagonals,

x and y are vectors of length n.

hbmv supports the following precisions.

T

std::complex<float>

std::complex<double>

## hbmv (Buffer Version)#

Syntax

namespace oneapi::mkl::blas::column_major {
void hbmv(sycl::queue &queue,
onemkl::uplo upper_lower,
std::int64_t n,
std::int64_t k,
T alpha,
sycl::buffer<T,1> &a,
std::int64_t lda,
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 hbmv(sycl::queue &queue,
onemkl::uplo upper_lower,
std::int64_t n,
std::int64_t k,
T alpha,
sycl::buffer<T,1> &a,
std::int64_t lda,
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.

upper_lower

Specifies whether A is upper or lower triangular. See oneMKL defined datatypes for more details.

n

Number of rows and columns of A. Must be at least zero.

k

Number of super-diagonals of the matrix A. Must be at least zero.

alpha

Scaling factor for the matrix-vector product.

a

Buffer holding input matrix A. Must have size at least lda*n. See Matrix Storage for more details.

lda

Leading dimension of matrix A. Must be at least (k + 1), and positive.

x

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

incx

Stride of vector x.

beta

Scaling factor for vector y.

y

Buffer holding input/output 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.

Throws

This routine shall throw the following exceptions if the associated condition is detected. An implementation may throw additional implementation-specific exception(s) in case of error conditions not covered here.

oneapi::mkl::invalid_argument

oneapi::mkl::unsupported_device

oneapi::mkl::unimplemented

## hbmv (USM Version)#

Syntax

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

namespace oneapi::mkl::blas::row_major {
sycl::event hbmv(sycl::queue &queue,
onemkl::uplo upper_lower,
std::int64_t n,
std::int64_t k,
T alpha,
const T *a,
std::int64_t lda,
const T *x,
std::int64_t incx,
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.

upper_lower

Specifies whether A is upper or lower triangular. See oneMKL defined datatypes for more details.

n

Number of rows and columns of A. Must be at least zero.

k

Number of super-diagonals of the matrix A. Must be at least zero.

alpha

Scaling factor for the matrix-vector product.

a

Pointer to the input matrix A. The array holding input matrix A must have size at least lda*n. See Matrix Storage for more details.

lda

Leading dimension of matrix A. Must be at least (k + 1), and positive.

x

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

incx

Stride of vector x.

beta

Scaling factor for vector y.

y

Pointer to input/output vector y. The array holding input/output 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.

Throws

This routine shall throw the following exceptions if the associated condition is detected. An implementation may throw additional implementation-specific exception(s) in case of error conditions not covered here.

oneapi::mkl::invalid_argument

oneapi::mkl::unsupported_device