dlartg-f(3)

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 is DOUBLE PRECISION
 The first component of vector to be rotated.

 G is DOUBLE PRECISION
 The second component of vector to be rotated.

 CS is DOUBLE PRECISION
 The cosine of the rotation.

 SN is DOUBLE PRECISION
 The sine of the rotation.

 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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