1DLARTG(1)           LAPACK auxiliary routine (version 3.1)           DLARTG(1)
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NAME

6       DLARTG - a plane rotation so that   [ CS SN ]
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SYNOPSIS

9       SUBROUTINE DLARTG( F, G, CS, SN, R )
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11           DOUBLE         PRECISION CS, F, G, R, SN
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PURPOSE

14       DLARTG generate a plane rotation so that
15          [ -SN  CS  ]     [ G ]     [ 0 ]
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17       This  is  a  slower,  more accurate version of the BLAS1 routine DROTG,
18       with the following other differences:
19          F and G are unchanged on return.
20          If G=0, then CS=1 and SN=0.
21          If F=0 and (G .ne. 0), then CS=0 and SN=1 without doing any
22             floating point operations (saves work in DBDSQR when
23             there are zeros on the diagonal).
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25       If F exceeds G in magnitude, CS will be positive.
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ARGUMENTS

29       F       (input) DOUBLE PRECISION
30               The first component of vector to be rotated.
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32       G       (input) DOUBLE PRECISION
33               The second component of vector to be rotated.
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35       CS      (output) DOUBLE PRECISION
36               The cosine of the rotation.
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38       SN      (output) DOUBLE PRECISION
39               The sine of the rotation.
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41       R       (output) DOUBLE PRECISION
42               The nonzero component of the rotated vector.
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44               This version has a few  statements  commented  out  for  thread
45               safety  (machine parameters are computed on each entry). 10 feb
46               03, SJH.
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50 LAPACK auxiliary routine (versionNo3v.e1m)ber 2006                       DLARTG(1)