slartg(3S)

NAME
     SLARTG - generate a plane rotation so that  [ CS SN ]

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

         REAL           CS, 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
     SLARTG generate a plane rotation so that [ CS SN ] . [ F ] = [ R ] where
     CS**2 + SN**2 = 1.    [ -SN  CS  ]     [ G ]     [ 0 ]

     This is a slower, more accurate version of the BLAS1 routine SROTG, with
     the following other differences:
        F and G are unchanged on return.
        If G=0, then CS=1 and SN=0.
        If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any
           floating point operations (saves work in SBDSQR when
           there are zeros on the diagonal).

     If F exceeds G in magnitude, CS will be positive.


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

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

     CS      (output) REAL
             The cosine of the rotation.

     SN      (output) REAL
             The sine of the rotation.

     R       (output) REAL
             The nonzero component of the rotated vector.
SEE ALSO
     INTRO_LAPACK(3S), INTRO_SCSL(3S)

     This man page is available only online.