# dlartgs.f man page

dlartgs.f

## Synopsis

### Functions/Subroutines

subroutine **dlartgs** (X, Y, SIGMA, CS, SN)**DLARTGS** generates a plane rotation designed to introduce a bulge in implicit QR iteration for the bidiagonal SVD problem.

## Function/Subroutine Documentation

### subroutine dlartgs (double precision X, double precision Y, double precision SIGMA, double precision CS, double precision SN)

**DLARTGS** generates a plane rotation designed to introduce a bulge in implicit QR iteration for the bidiagonal SVD problem.

**Purpose:**

DLARTGS generates a plane rotation designed to introduce a bulge in Golub-Reinsch-style implicit QR iteration for the bidiagonal SVD problem. X and Y are the top-row entries, and SIGMA is the shift. The computed CS and SN define a plane rotation satisfying [ CS SN ] . [ X^2 - SIGMA ] = [ R ], [ -SN CS ] [ X * Y ] [ 0 ] with R nonnegative. If X^2 - SIGMA and X * Y are 0, then the rotation is by PI/2.

**Parameters:**-
*X*X is DOUBLE PRECISION The (1,1) entry of an upper bidiagonal matrix.

*Y*Y is DOUBLE PRECISION The (1,2) entry of an upper bidiagonal matrix.

*SIGMA*SIGMA is DOUBLE PRECISION The shift.

*CS*CS is DOUBLE PRECISION The cosine of the rotation.

*SN*SN is DOUBLE PRECISION The sine of the rotation.

**Author:**-
Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**November 2017

Definition at line 92 of file dlartgs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

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

Tue Nov 14 2017 Version 3.8.0 LAPACK