clartg.f (3)

Functions/Subroutines

subroutine clartg (F, G, CS, SN, R)

CLARTG generates a plane rotation with real cosine and complex sine.

subroutine clartg (complexF, complexG, realCS, complexSN, complexR)

CLARTG generates a plane rotation with real cosine and complex sine.

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.

Parameters:

F

          F is COMPLEX
          The first component of vector to be rotated.

G

          G is COMPLEX
          The second component of vector to be rotated.

CS

          CS is REAL
          The cosine of the rotation.

SN

          SN is COMPLEX
          The sine of the rotation.

R

          R is COMPLEX
          The nonzero component of the rotated vector.

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2013

Further Details:

  3-5-96 - Modified with a new algorithm by W. Kahan and J. Demmel

  This version has a few statements commented out for thread safety
  (machine parameters are computed on each entry). 10 feb 03, SJH.

Definition at line 104 of file clartg.f.

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