DLARTGS (3)  Linux Manuals
NAME
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 precisionX, double precisionY, double precisionSIGMA, double precisionCS, double precisionSN)
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 GolubReinschstyle implicit QR iteration for the bidiagonal SVD problem. X and Y are the toprow 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.
YY is DOUBLE PRECISION The (1,2) entry of an upper bidiagonal matrix.
SIGMASIGMA is DOUBLE PRECISION The shift.
CSCS is DOUBLE PRECISION The cosine of the rotation.
SNSN is DOUBLE PRECISION 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 dlartgs.f.
Author
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