drotmg(l) - Linux man page

Name

DROTMG - CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS THE SECOND COMPONENT OF THE 2-VECTOR (DSQRT(DD1)*DX1,DSQRT(DD2)*

Synopsis

SUBROUTINE DROTMG(DD1,DD2,DX1,DY1,DPARAM)

DOUBLE

PRECISION DD1,DD2,DX1,DY1

DOUBLE

PRECISION DPARAM(5)

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.

Arguments

DD1 (input/output) DOUBLE PRECISION

DD2 (input/output) DOUBLE PRECISION

DX1 (input/output) DOUBLE PRECISION

DY1 (input) DOUBLE PRECISION

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