CXML

LAPACK version 3.0

slartg(3)

PURPOSE

SLARTG - generate a plane rotation so that [ CS SN ]

SYNTAX

SUBROUTINE SLARTG( F, G, CS, SN, R ) REAL CS, F, G, R, SN

DESCRIPTION

SLARTG generate a plane rotation so that [ CS SN ] . [ F ] = [ R ] where CS**2 + SN**2 = 1. [ -SN CS ] [ G ] [ 0 ] This is a slower, more accurate version of the BLAS1 routine SROTG, with the following other differences: F and G are unchanged on return. If G=0, then CS=1 and SN=0. If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any floating point operations (saves work in SBDSQR when there are zeros on the diagonal). If F exceeds G in magnitude, CS will be positive.

ARGUMENTS

F (input) REAL The first component of vector to be rotated. G (input) REAL The second component of vector to be rotated. CS (output) REAL The cosine of the rotation. SN (output) REAL The sine of the rotation. R (output) REAL The nonzero component of the rotated vector.

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