slartg (l) - Linux Manuals

slartg: generate a plane rotation so that [ CS SN ]

NAME

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

SYNOPSIS

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

    
REAL CS, F, G, R, SN

PURPOSE

SLARTG generate a plane rotation so that
[ -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. This version has a few statements commented out for thread safety (machine parameters are computed on each entry). 10 feb 03, SJH.

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