Loading...
Searching...
No Matches

## slartgp()

subroutine slartgp | ( | real | f,
|  | real | g,
|  | real | cs,
|  | real | sn,
|  | real | r )

SLARTGP generates a plane rotation so that the diagonal is nonnegative.

Download SLARTGP + dependencies [TGZ] [ZIP] [TXT]

Purpose:

      !>
      !> SLARTGP generates 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 Level 1 BLAS 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.
      !>
      !> The sign is chosen so that R >= 0.
      !>

Parameters

  [in]

  F

      !>          F is REAL
      !>          The first component of vector to be rotated.
      !>

  [in]

  G

      !>          G is REAL
      !>          The second component of vector to be rotated.
      !>

  [out]

  CS

      !>          CS is REAL
      !>          The cosine of the rotation.
      !>

  [out]

  SN

      !>          SN is REAL
      !>          The sine of the rotation.
      !>

  [out]

  R

      !>          R is REAL
      !>          The nonzero component of the rotated vector.
      !>
      !>  This version has a few statements commented out for thread safety
      !>  (machine parameters are computed on each entry). 10 feb 03, SJH.
      !>

Author
  Univ. of Tennessee
  Univ. of California Berkeley
  Univ. of Colorado Denver
  NAG Ltd.