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LAPACK
3.4.1
LAPACK: Linear Algebra PACKage
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Go to the source code of this file.
Functions/Subroutines | |
subroutine | SLARTGS (X, Y, SIGMA, CS, SN) |
SLARTGS |
subroutine SLARTGS | ( | REAL | X, |
REAL | Y, | ||
REAL | SIGMA, | ||
REAL | CS, | ||
REAL | SN | ||
) |
SLARTGS
Download SLARTGS + dependencies [TGZ] [ZIP] [TXT]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.
[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.