dlartg.f(3) LAPACK dlartg.f(3)
NAME
dlartg.f -
SYNOPSIS
Functions/Subroutines
subroutine dlartg (F, G, CS, SN, R)
DLARTG generates a plane rotation with real cosine and real sine.
Function/Subroutine Documentation
subroutine dlartg (double precisionF, double precisionG, double precisionCS, double precisionSN, double precisionR)
DLARTG generates a plane rotation with real cosine and real sine.
Purpose:
DLARTG generate a plane rotation so that
[ CS SN ] . [ F ] = [ R ] where CS**2 + SN**2 = 1.
[ -SN CS ] [ G ] [ 0 ]
This is a slower, more accurate version of the BLAS1 routine DROTG,
with the following other differences:
F and G are unchanged on return.
If G=0, then CS=1 and SN=0.
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).
If F exceeds G in magnitude, CS will be positive.
Parameters:
F
F is DOUBLE PRECISION
The first component of vector to be rotated.
G
G is DOUBLE PRECISION
The second component of vector to be rotated.
CS
CS is DOUBLE PRECISION
The cosine of the rotation.
SN
SN is DOUBLE PRECISION
The sine of the rotation.
R
R is DOUBLE PRECISION
The nonzero component of the rotated vector.
This version has a few statements commented out for thread safety
(machine parameters are computed on each entry). 10 feb 03, SJH.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 98 of file dlartg.f.
Author
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Version 3.4.2 Tue Sep 25 2012 dlartg.f(3)