rotm¶
Performs modified Givens rotation of points in the plane.
Syntax
-
void
rotm
(queue &exec_queue, std::int64_t n, buffer<T, 1> &x, std::int64_t incx, buffer<T, 1> &y, std::int64_t incy, buffer<T, 1> ¶m)¶
rotm
supports the following precisions and devices.
T |
Devices Supported |
---|---|
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
Description
Given two vectors x
and y
, each vector element of these
vectors is replaced as follows:
\left[ \begin{array}{ccc} x_i \\ y_i \end{array} \right] = H \left[ \begin{array}{ccc} x_i \\ y_i \end{array} \right]
for i
from 1 to n
, where H
is a modified Givens
transformation matrix.
Input Parameters
- exec_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 and Vector 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 and Vector 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
,param
[1-4] contain h11,h21, h12,h22 respectively, the components ofthe modified Givens transformation matrixH
.Depending on the values of
flag
, thecomponents ofH
are set as follows:flag = -1.0
:H = \left[ \begin{array}{ccc} h_{11} & h_{12} \\ h_{21} & h_{22} \end{array} \right]
flag = 0.0
:H = \left[ \begin{array}{ccc} 1.0 & h_{12} \\ h_{21} & 1.0 \end{array} \right]
flag = 1.0
:H = \left[ \begin{array}{ccc} h_{11} & 1.0 \\ -1.0 & h_{22} \end{array} \right]
flag = -2.0
:H = \left[ \begin{array}{ccc} 1.0 & 0.0 \\ 0.0 & 1.0 \end{array} \right]
In the last three cases, the matrix entries of 1.0, -1.0, 0.0 are assumed based on the value of
flag
and are not required to be set in theparam
vector.
Output Parameters
- x
Buffer holding updated buffer
x
.- y
Buffer holding updated buffer
y
.