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rotmg(3) LAPACK rotmg(3)

NAME

rotmg - rotmg: generate modified (fast) plane rotation

SYNOPSIS

Functions


subroutine drotmg (dd1, dd2, dx1, dy1, dparam)
DROTMG subroutine srotmg (sd1, sd2, sx1, sy1, sparam)
SROTMG

Detailed Description

Function Documentation

subroutine drotmg (double precision dd1, double precision dd2, double precision dx1, double precision dy1, 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.

subroutine srotmg (real sd1, real sd2, real sx1, real sy1, real, dimension(5) sparam)

SROTMG

Purpose:


CONSTRUCT THE MODIFIED GIVENS TRANSFORMATION MATRIX H WHICH ZEROS
THE SECOND COMPONENT OF THE 2-VECTOR (SQRT(SD1)*SX1,SQRT(SD2)*> SY2)**T.
WITH SPARAM(1)=SFLAG, H HAS ONE OF THE FOLLOWING FORMS..
SFLAG=-1.E0 SFLAG=0.E0 SFLAG=1.E0 SFLAG=-2.E0
(SH11 SH12) (1.E0 SH12) (SH11 1.E0) (1.E0 0.E0)
H=( ) ( ) ( ) ( )
(SH21 SH22), (SH21 1.E0), (-1.E0 SH22), (0.E0 1.E0).
LOCATIONS 2-4 OF SPARAM CONTAIN SH11,SH21,SH12, AND SH22
RESPECTIVELY. (VALUES OF 1.E0, -1.E0, OR 0.E0 IMPLIED BY THE
VALUE OF SPARAM(1) ARE NOT STORED IN SPARAM.)
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 SD1 AND SD2. ALL ACTUAL SCALING OF DATA IS DONE USING GAM.

Parameters

SD1


SD1 is REAL

SD2


SD2 is REAL

SX1


SX1 is REAL

SY1


SY1 is REAL

SPARAM


SPARAM is REAL array, dimension (5)
SPARAM(1)=SFLAG
SPARAM(2)=SH11
SPARAM(3)=SH21
SPARAM(4)=SH12
SPARAM(5)=SH22

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Author

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Sat Dec 9 2023 21:42:18 Version 3.12.0