# rotm¶

Performs modified Givens rotation of points in the plane.

Description

Given two vectors x and y, each vector element of these vectors is replaced as follows:

$\begin{split}\begin{bmatrix}x_i \\ y_i\end{bmatrix}= H \begin{bmatrix}x_i \\ y_i\end{bmatrix}\end{split}$

for i from 1 to n, where H is a modified Givens transformation matrix.

rotm supports the following precisions.

T

float

double

## rotm (Buffer Version)¶

Syntax

namespace oneapi::mkl::blas::column_major {
void rotm(sycl::queue &queue,
std::int64_t n,
sycl::buffer<T,1> &x,
std::int64_t incx,
sycl::buffer<T,1> &y,
std::int64_t incy,
sycl::buffer<T,1> &param)
}

namespace oneapi::mkl::blas::row_major {
void rotm(sycl::queue &queue,
std::int64_t n,
sycl::buffer<T,1> &x,
std::int64_t incx,
sycl::buffer<T,1> &y,
std::int64_t incy,
sycl::buffer<T,1> &param)
}


Input Parameters

queue

The queue where the routine should be executed.

n

Number of elements in vector x.

x

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

incx

Stride of vector x.

y

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

incy

Stride of vector y.

param

Buffer holding an array of size 5.

The elements of the param array are:

param[0] contains a switch, flag. The other array elements param[1-4] contain the components of the modified Givens transformation matrix H: h11, h21, h12, and h22, respectively.

Depending on the values of flag, the components of H are set as follows:

flag = -1.0:
$\begin{split}H=\begin{bmatrix}h_{11} & h_{12} \\ h_{21} & h_{22}\end{bmatrix}\end{split}$
flag = 0.0:
$\begin{split}H=\begin{bmatrix}1.0 & h_{12} \\ h_{21} & 1.0\end{bmatrix}\end{split}$
flag = 1.0:
$\begin{split}H=\begin{bmatrix}h_{11} & 1.0 \\ -1.0 & h_{22}\end{bmatrix}\end{split}$
flag = -2.0:
$\begin{split}H=\begin{bmatrix}1.0 & 0.0 \\ 0.0 & 1.0\end{bmatrix}\end{split}$

In the last three cases, the matrix entries of 1.0, -1.0, and 0.0 are assumed based on the value of flag and are not required to be set in the param vector.

Output Parameters

x

Buffer holding updated buffer x.

y

Buffer holding updated buffer y.

## rotm (USM Version)¶

Syntax

namespace oneapi::mkl::blas::column_major {
sycl::event rotm(sycl::queue &queue,
std::int64_t n,
T *x,
std::int64_t incx,
T *y,
std::int64_t incy,
T *param,
const std::vector<sycl::event> &dependencies = {})
}

namespace oneapi::mkl::blas::row_major {
sycl::event rotm(sycl::queue &queue,
std::int64_t n,
T *x,
std::int64_t incx,
T *y,
std::int64_t incy,
T *param,
const std::vector<sycl::event> &dependencies = {})
}


Input Parameters

queue

The queue where the routine should be executed.

n

Number of elements in vector x.

x

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

incx

Stride of vector x.

yparam

Pointer to the input vector y. The array holding the vector y must be of size at least (1 + (n - 1)*abs(incy)). See Matrix Storage for more details.

incy

Stride of vector y.

param

Buffer holding an array of size 5.

The elements of the param array are:

param[0] contains a switch, flag. The other array elements param[1-4] contain the components of the modified Givens transformation matrix H: h11, h21, h12, and h22, respectively.

Depending on the values of flag, the components of H are set as follows:

flag = -1.0:
$\begin{split}H=\begin{bmatrix}h_{11} & h_{12} \\ h_{21} & h_{22}\end{bmatrix}\end{split}$
flag = 0.0:
$\begin{split}H=\begin{bmatrix}1.0 & h_{12} \\ h_{21} & 1.0\end{bmatrix}\end{split}$
flag = 1.0:
$\begin{split}H=\begin{bmatrix}h_{11} & 1.0 \\ -1.0 & h_{22}\end{bmatrix}\end{split}$
flag = -2.0:
$\begin{split}H=\begin{bmatrix}1.0 & 0.0 \\ 0.0 & 1.0\end{bmatrix}\end{split}$

In the last three cases, the matrix entries of 1.0, -1.0, and 0.0 are assumed based on the value of flag and are not required to be set in the param vector.

dependencies

List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.

Output Parameters

x

Pointer to the updated array x.

y

Pointer to the updated array y.

Return Values

Output event to wait on to ensure computation is complete.

Parent topic: BLAS Level 1 Routines