lartgs - lartgs: generate plane rotation for bidiag SVD

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subroutinedlartgs(doubleprecisionx,doubleprecisiony,doubleprecisionsigma,doubleprecisioncs,doubleprecisionsn)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. ParametersX 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. subroutineslartgs(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. ParametersX 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.

lartgs - lartgs: generate plane rotation for bidiag SVD

Functions 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. 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.