Visible to Intel only — GUID: GUID-C0A38FCD-1A6C-432D-BC2F-929B6AB5DB23
Visible to Intel only — GUID: GUID-C0A38FCD-1A6C-432D-BC2F-929B6AB5DB23
?rotg
Computes the parameters for a Givens rotation.
Syntax
call srotg(a, b, c, s)
call drotg(a, b, c, s)
call crotg(a, b, c, s)
call zrotg(a, b, c, s)
call rotg(a, b, c, s)
Include Files
- mkl.fi, blas.f90
Description
Given the Cartesian coordinates (a, b) of a point, these routines return the parameters c, s, r, and z associated with the Givens rotation. The parameters c and s define a unitary matrix such that:
The parameter z is defined such that if |a| > |b|, z is s; otherwise if c is not 0 z is 1/c; otherwise z is 1.
See a more accurate LAPACK version ?lartg.
Input Parameters
- a
-
REAL for srotg
DOUBLE PRECISION for drotg
COMPLEX for crotg
DOUBLE COMPLEX for zrotg
Provides the x-coordinate of the point p.
- b
-
REAL for srotg
DOUBLE PRECISION for drotg
COMPLEX for crotg
DOUBLE COMPLEX for zrotg
Provides the y-coordinate of the point p.
Output Parameters
- a
-
Contains the parameter r associated with the Givens rotation.
- b
-
Contains the parameter z associated with the Givens rotation.
- c
-
REAL for srotg
DOUBLE PRECISION for drotg
REAL for crotg
DOUBLE PRECISION for zrotg
Contains the parameter c associated with the Givens rotation.
- s
-
REAL for srotg
DOUBLE PRECISION for drotg
COMPLEX for crotg
DOUBLE COMPLEX for zrotg
Contains the parameter s associated with the Givens rotation.