# slartgs.f man page

slartgs.f —

## Synopsis

### Functions/Subroutines

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

## Function/Subroutine Documentation

### subroutine slartgs (realX, realY, realSIGMA, realCS, realSN)

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

**Purpose:**

SLARTGS 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 REAL The (1,1) entry of an upper bidiagonal matrix.

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

*SIGMA*SIGMA is REAL The shift.

*CS*CS is REAL The cosine of the rotation.

*SN*SN is REAL The sine of the rotation.

**Author:**-
Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

**Date:**September 2012

Definition at line 91 of file slartgs.f.

## Author

Generated automatically by Doxygen for LAPACK from the source code.

## Referenced By

slartgs(3) is an alias of slartgs.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK