clartg(3S)

NAME
     CLARTG - generate a plane rotation so that  [ CS SN ] [ F ] [ R ] [ __ ]

SYNOPSIS
     SUBROUTINE CLARTG( F, G, CS, SN, R )

         REAL           CS

         COMPLEX        F, G, R, SN

IMPLEMENTATION
     These routines are part of the SCSL Scientific Library and can be loaded
     using either the -lscs or the -lscs_mp option.  The -lscs_mp option
     directs the linker to use the multi-processor version of the library.

     When linking to SCSL with -lscs or -lscs_mp, the default integer size is
     4 bytes (32 bits). Another version of SCSL is available in which integers
     are 8 bytes (64 bits).  This version allows the user access to larger
     memory sizes and helps when porting legacy Cray codes.  It can be loaded
     by using the -lscs_i8 option or the -lscs_i8_mp option. A program may use
     only one of the two versions; 4-byte integer and 8-byte integer library
     calls cannot be mixed.

PURPOSE
     CLARTG generates a plane rotation so that [ CS SN ] [ F ] [ R ] [ __ ] .
     [ ] = [ ] where CS**2 + |SN|**2 = 1.    [ -SN  CS  ]     [ G ]     [ 0 ]

     This is a faster version of the BLAS1 routine CROTG, except for the
     following differences:
        F and G are unchanged on return.
        If G=0, then CS=1 and SN=0.
        If F=0, then CS=0 and SN is chosen so that R is real.


ARGUMENTS
     F       (input) COMPLEX
             The first component of vector to be rotated.

     G       (input) COMPLEX
             The second component of vector to be rotated.

     CS      (output) REAL
             The cosine of the rotation.

     SN      (output) COMPLEX
             The sine of the rotation.

     R       (output) COMPLEX
             The nonzero component of the rotated vector.
FURTHER DETAILS
     3-5-96 - Modified with a new algorithm by W. Kahan and J. Demmel


SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

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