drotmg.f man page

drotmg.f —

Synopsis

Functions/Subroutines

subroutine drotmg (DD1, DD2, DX1, DY1, DPARAM)
DROTMG

Function/Subroutine Documentation

subroutine drotmg (double precisionDD1, double precisionDD2, double precisionDX1, double precisionDY1, double precision, dimension(5)DPARAM)

DROTMG Purpose:

CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS
THE SECOND COMPONENT OF THE 2-VECTOR  (DSQRT(DD1)*DX1,DSQRT(DD2)*>    DY2)**T.
WITH DPARAM(1)=DFLAG, H HAS ONE OF THE FOLLOWING FORMS..

DFLAG=-1.D0     DFLAG=0.D0        DFLAG=1.D0     DFLAG=-2.D0

  (DH11  DH12)    (1.D0  DH12)    (DH11  1.D0)    (1.D0  0.D0)
H=(          )    (          )    (          )    (          )
  (DH21  DH22),   (DH21  1.D0),   (-1.D0 DH22),   (0.D0  1.D0).
LOCATIONS 2-4 OF DPARAM CONTAIN DH11, DH21, DH12, AND DH22
RESPECTIVELY. (VALUES OF 1.D0, -1.D0, OR 0.D0 IMPLIED BY THE
VALUE OF DPARAM(1) ARE NOT STORED IN DPARAM.)

THE VALUES OF GAMSQ AND RGAMSQ SET IN THE DATA STATEMENT MAY BE
INEXACT.  THIS IS OK AS THEY ARE ONLY USED FOR TESTING THE SIZE
OF DD1 AND DD2.  ALL ACTUAL SCALING OF DATA IS DONE USING GAM.

Parameters:

DD1

DD1 is DOUBLE PRECISION

DD2

DD2 is DOUBLE PRECISION

DX1

DX1 is DOUBLE PRECISION

DY1

DY1 is DOUBLE PRECISION

DPARAM

     DPARAM is DOUBLE PRECISION array, dimension 5
DPARAM(1)=DFLAG
DPARAM(2)=DH11
DPARAM(3)=DH21
DPARAM(4)=DH12
DPARAM(5)=DH22

Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 91 of file drotmg.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

drotmg(3) is an alias of drotmg.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK