LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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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. 
subroutine slartgs  (  real  X, 
real  Y,  
real  SIGMA,  
real  CS,  
real  SN  
) 
SLARTGS generates a plane rotation designed to introduce a bulge in implicit QR iteration for the bidiagonal SVD problem.
Download SLARTGS + dependencies [TGZ] [ZIP] [TXT]SLARTGS 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.
[in]  X  X is REAL The (1,1) entry of an upper bidiagonal matrix. 
[in]  Y  Y is REAL The (1,2) entry of an upper bidiagonal matrix. 
[in]  SIGMA  SIGMA is REAL The shift. 
[out]  CS  CS is REAL The cosine of the rotation. 
[out]  SN  SN is REAL The sine of the rotation. 
Definition at line 91 of file slartgs.f.