Developer Reference for Intel® oneAPI Math Kernel Library for Fortran
?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, mkl_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 (Generates a plane rotation with real cosine and real/complex sine.) .
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.