Contents

# hpr2

Performs a rank-2 update of a hermitian packed matrix.

## Description

The
hpr2
routines compute two scalar-vector-vector products and add them to a hermitian packed matrix. The operation is defined as:
where:
• alpha
is a scalar
• A
is
n
x
n
hermitian matrix, supplied in packed form
• x
and
y
are vectors of length
n
hpr2
supports the following precisions:
T
std::complex<float>
std::complex<double>

## hpr2 (Buffer Version)

Syntax
``````namespace oneapi::mkl::blas::column_major {
void hpr2(sycl::queue &queue,
oneapi::mkl::uplo upper_lower,
std::int64_t n,
T alpha,
sycl::buffer<T,1> &x,
std::int64_t incx,
sycl::buffer<T,1> &y,
std::int64_t incy,
sycl::buffer<T,1> &a)
}``````
``````namespace oneapi::mkl::blas::row_major {
void hpr2(sycl::queue &queue,
oneapi::mkl::uplo upper_lower,
std::int64_t n,
T alpha,
sycl::buffer<T,1> &x,
std::int64_t incx,
sycl::buffer<T,1> &y,
std::int64_t incy,
sycl::buffer<T,1> &a)
}``````
Input Parameters
queue
The queue where the routine should be executed.
upper_lower
Specifies whether matrix
A
is upper or lower triangular. See Data Types for more details.
n
Number of rows and columns of matrix
A
. Must be at least zero.
alpha
Scaling factor for the matrix-vector product.
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/output 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
.
a
Buffer holding input matrix
A
. Size of the buffer must be at least (
n
*(
n
-1))/2. See Matrix Storage for more details.
The imaginary parts of the diagonal elements need not be set and are assumed to be zero.
Output Parameters
a
Buffer holding updated upper triangular part of the hermitian matrix
A
if
upper_lower=upper
, or updated lower triangular part of the hermitian matrix
A
if
upper_lower=lower
.
The imaginary parts of the diagonal elements are set to zero.

## hpr2 (USM Version)

Syntax
``````namespace oneapi::mkl::blas::column_major {
sycl::event hpr2(sycl::queue &queue,
oneapi::mkl::uplo upper_lower,
std::int64_t n,
T alpha,
const T *x,
std::int64_t incx,
const T *y,
std::int64_t incy,
T *a,
const std::vector<sycl::event> &dependencies = {})
}``````
``````namespace oneapi::mkl::blas::row_major {
sycl::event hpr2(sycl::queue &queue,
oneapi::mkl::uplo upper_lower,
std::int64_t n,
T alpha,
const T *x,
std::int64_t incx,
const T *y,
std::int64_t incy,
T *a,
const std::vector<sycl::event> &dependencies = {})
}``````
Input Parameters
queue
The queue where the routine should be executed.
upper_lower
Specifies whether matrix
A
is upper or lower triangular. See Data Types for more details.
n
Number of rows and columns of matrix
A
. Must be at least zero.
alpha
Scaling factor for the matrix-vector product.
x
Pointer to input vector
x
. Size of the array holding input 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/output vector
y
. Size of the array holding input/output vector
y
must be at least (1 + (
n
- 1)*abs(
incy
)). See Matrix Storage for more details.
incy
Stride of vector
y
.
a
Pointer to input matrix
A
. Size of the array holding input matrix
A
must be at least (
n
*(
n
-1))/2. See Matrix Storage for more details.
The imaginary parts of the diagonal elements need not be set and are assumed to be zero.
dependencies
List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.
Output Parameters
a
Pointer to updated upper triangular part of the hermitian matrix
A
if
upper_lower=upper
, or updated lower triangular part of the hermitian matrix
A
if
upper_lower=lower
.
The imaginary parts of the diagonal elements are set to zero.
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.