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LAPACK: Linear Algebra PACKage
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slartgp.f File Reference

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Functions/Subroutines

subroutine slartgp (F, G, CS, SN, R)
 SLARTGP generates a plane rotation so that the diagonal is nonnegative.

Function/Subroutine Documentation

subroutine slartgp ( real  F,
real  G,
real  CS,
real  SN,
real  R 
)

SLARTGP generates a plane rotation so that the diagonal is nonnegative.

Download SLARTGP + dependencies [TGZ] [ZIP] [TXT]
Purpose:
 SLARTGP generates 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 Level 1 BLAS 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.

 The sign is chosen so that R >= 0.
Parameters
[in]F
          F is REAL
          The first component of vector to be rotated.
[in]G
          G is REAL
          The second component of vector to be rotated.
[out]CS
          CS is REAL
          The cosine of the rotation.
[out]SN
          SN is REAL
          The sine of the rotation.
[out]R
          R is 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.
Author
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date
September 2012

Definition at line 96 of file slartgp.f.

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