# dlartg.f - Man Page

## 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 precision F, double precision G, double precision CS, double precision SN, double precision R)

**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:**December 2016

Definition at line 99 of file dlartg.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

The man page dlartg(3) is an alias of dlartg.f(3).

Tue Nov 14 2017 Version 3.8.0 LAPACK