dlartg(3)

NAME

dlartg.f –

SYNOPSIS

Functions/Subroutines

subroutine dlartg (F, G, CS, SN, R)
DLARTG generates a plane rotation with real cosine and real sine.

Function/Subroutine Documentation

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

DLARTG generates a plane rotation with real cosine and real sine.

Purpose:

DLARTG 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 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 without doing any floating point operations(saves work in DBDSQR when there are zeros on the diagonal).If F exceeds G in magnitude, CS will be positive.

 

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 98 of file dlartg.f.

Author

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