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.TH DLARTG l "15 June 2000" "LAPACK version 3.0" ")"
.SH NAME
DLARTG - generate a plane rotation so that [ CS SN ]
.SH SYNOPSIS
.TP 19
SUBROUTINE DLARTG(
F, G, CS, SN, R )
.TP 19
.ti +4
DOUBLE
PRECISION CS, F, G, R, SN
.SH PURPOSE
DLARTG generate a plane rotation so that [ CS SN ] . [ F ] = [ R ] where CS**2 + SN**2 = 1. [ -SN CS ] [ G ] [ 0 ]
.br
This is a slower, more accurate version of the BLAS1 routine DROTG,
with the following other differences:
.br
F and G are unchanged on return.
.br
If G=0, then CS=1 and SN=0.
.br
If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any
floating point operations (saves work in DBDSQR when
there are zeros on the diagonal).
.br
If F exceeds G in magnitude, CS will be positive.
.br
.SH ARGUMENTS
.TP 8
F (input) DOUBLE PRECISION
The first component of vector to be rotated.
.TP 8
G (input) DOUBLE PRECISION
The second component of vector to be rotated.
.TP 8
CS (output) DOUBLE PRECISION
The cosine of the rotation.
.TP 8
SN (output) DOUBLE PRECISION
The sine of the rotation.
.TP 8
R (output) DOUBLE PRECISION
The nonzero component of the rotated vector.
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