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dlartgp.f(3) LAPACK dlartgp.f(3)

NAME

dlartgp.f -

SYNOPSIS

Functions/Subroutines


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

Function/Subroutine Documentation

subroutine dlartgp (double precisionF, double precisionG, double precisionCS, double precisionSN, double precisionR)

DLARTGP generates a plane rotation so that the diagonal is nonnegative.
Purpose: 
 DLARTGP 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 DROTG,
 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:
F 
          F is DOUBLE PRECISION
          The first component of vector to be rotated.
G 
          G is DOUBLE PRECISION
          The second component of vector to be rotated.
CS 
          CS is DOUBLE PRECISION
          The cosine of the rotation.
SN 
          SN is DOUBLE PRECISION
          The sine of the rotation.
R 
          R is DOUBLE PRECISION
          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 dlartgp.f.

Author

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