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Visible to Intel only — GUID: GUID-A80B4932-AD08-4E21-89FC-50CC1622AB70
?lartgp
Generates a plane rotation.
Syntax
call slartgp( f, g, cs, sn, r )
call dlartgp( f, g, cs, sn, r )
call lartgp( f,g,cs,sn,r )
Include Files
- mkl.fi
Description
The routine generates a plane rotation so that
where cs2 + sn2 = 1
This is a slower, more accurate version of the BLAS Level 1 routine ?rotg, except for the following differences:
f and g are unchanged on return.
If g=0, then cs=(+/-)1 and sn=0.
If f=0 and g≠ 0, then cs=0 and sn=(+/-)1.
The sign is chosen so that r≥ 0.
Input Parameters
The data types are given for the Fortran interface.
- f, g
-
REAL for slartgp
DOUBLE PRECISION for dlartgp
The first and second component of the vector to be rotated.
Output Parameters
- cs
-
REAL for slartgp
DOUBLE PRECISION for dlartgp
The cosine of the rotation.
- sn
-
REAL for slartgp
DOUBLE PRECISION for dlartgp
The sine of the rotation.
- r
-
REAL for slartgp
DOUBLE PRECISION for dlartgp
The nonzero component of the rotated vector.
- info
-
INTEGER. If info = 0, the execution is successful.
If info =-1,f is NaN.
If info = -2, g is NaN.
LAPACK 95 Interface Notes
Routines in Fortran 95 interface have fewer arguments in the calling sequence than their FORTRAN 77 counterparts. For general conventions applied to skip redundant or reconstructible arguments, see LAPACK 95 Interface Conventions.
Specific details for the routine ?lartgp interface are as follows:
- f
-
Holds the first component of the vector to be rotated.
- g
-
Holds the second component of the vector to be rotated.
- cs
-
Holds the cosine of the rotation.
- sn
-
Holds the sine of the rotation.
- r
-
Holds the nonzero component of the rotated vector.