# 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

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