drotmg - Fast Givens Rotation Parameters (DBL) VI
- Updated2025-07-30
- 3 minute(s) read
Calculates a fast Givens rotation matrix that zeros the y component of a two-element real vector and calculates the related parameters. You can use the output parameters in the drotm - Fast Givens Rotation (DBL) VI.
Inputs/Outputs
x
—
x is the real input x-component for the two-element vector.
y
—
y is the real input y-component for the two-element vector.
d1 in
—
d1 in is the real scale factor for x.
d2 in
—
d2 in is the real scale factor for y. 
rotation matrix flag
—
rotation matrix flag returns the flag that describes the form of Rotation Matrix. rotation matrix flag returns –2, –1, 0, or 1. 
r
—
r returns the x-component after the Givens rotation.
d1 out
—
d1 out returns the updated scale factor of the x-component.
d2 out
—
d2 out returns the updated scale factor of the y-component.
error
—
error returns any error or warning from the VI. You can wire error to the Error Cluster From Error Code VI to convert the error code or warning into an error cluster. 
Rotation Matrix
—
Rotation Matrix returns the 2 × 2 fast Givens rotation matrix. |
The VI calculates the fast Givens rotation parameters using the following equation:
where H is the fast Givens rotation matrix.
The fast Givens rotation matrix and scale parameters must satisfy the following equation:
The rotation matrix flag determines the structure and value of certain elements in Rotation Matrix H as follows:
| If rotation matrix flag is 1, H = |  |
| If rotation matrix flag is 0, H = |  |
| If rotation matrix flag is –1, H = |  |
| If rotation matrix flag is –2, H = |  |
where h11, h12, h21,and h22 are elements in Rotation Matrix.
Refer to the BLAS (Basic Linear Algebra Subprograms) website at netlib.org for more information on BLAS functions.
Examples
Refer to the following example files included with LabVIEW.
- labview\examples\Mathematics\Linear Algebra\QR decomposition update by Givens rotation.vi