# dlartgp.f - Man Page

SRC/dlartgp.f

## Synopsis

### Functions/Subroutines

subroutine **dlartgp** (f, g, cs, sn, r)**DLARTGP** generates a plane rotation so that the diagonal is nonnegative.

## Function/Subroutine Documentation

### subroutine dlartgp (double precision f, double precision g, double precision cs, double precision sn, double precision r)

**DLARTGP** generates a plane rotation so that the diagonal is nonnegative.

**Purpose:**

DLARTGP generates 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 Level 1 BLAS 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. The sign is chosen so that R >= 0.

**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.

Definition at line **94** of file **dlartgp.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 28 2023 12:08:42 Version 3.12.0 LAPACK