rotmg (USM Version)¶
Computes the parameters for a modified Givens rotation.
Syntax
-
event rotmg(queue &exec_queue, T \*d1, T \*d2, T \*x1, T \*y1, T \*param, const vector_class<event> &dependencies = {})
The USM version of rotmg
supports the following precisions and
devices.
T |
Devices Supported |
---|---|
|
Host, CPU, and GPU |
|
Host, CPU, and GPU |
Description
Given Cartesian coordinates (x
1, y
1) of an
input vector, the rotmg routines compute the components of a modified
Givens transformation matrix H
that zeros the y
-component of
the resulting vector:
\left[ \begin{array}{ccc} x1 \\ 0 \end{array} \right] = H \left[ \begin{array}{ccc} x1 & \sqrt{d1} \\ y1 & \sqrt{d2} \end{array} \right]
Input Parameters
- exec_queue
The queue where the routine should be executed.
- d1
Pointer to the scaling factor for the
x
-coordinate of the input vector.- d2
Pointer to the scaling factor for the
y
-coordinate of the input vector.- x1
Pointer to the
x
-coordinate of the input vector.- y1
Scalar specifying the
y
-coordinate of the input vector.- dependencies
List of events to wait for before starting computation, if any. If omitted, defaults to no dependencies.
Output Parameters
- d1
Pointer to the first diagonal element of the updated matrix.
- d2
Pointer to the second diagonal element of the updated matrix.
- x1
Pointer to the x-coordinate of the rotated vector before scaling
- param
Pointer to an array of size 5.
The elements of the
param
array are:param[0]
contains a switch,flag
. The other array elementsparam[1-4]
contain the components of the arrayH
:h
11,h
21,h
12, andh
22, respectively.Depending on the values of
flag
, the components 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, and 0.0 are assumed based on the value of
flag
and are not required to be set in theparam
vector.
Return Values
Output event to wait on to ensure computation is complete.