[Pkg-octave-devel] Bug in function acot

[Jakub Stryja]

Hello,
I have debian Sarge and I find bug in package octave2.1.

I have this packages:
  dpkg -l |grep octave
ii  octave         2.1.69-1       GNU Octave language for numerical 
computatio
ii  octave-ci      99.09-2        Contributed functions for the GNU Octave 
lan
ii  octave-epstk   2.1-1          GNU Octave encapsulated postscript 
toolkit
ii  octave-forge   2004.11.16-7   Contributed functions for GNU Octave 
from ht
ii  octave-plplot  5.3.1-4        Octave support for PLplot, a plotting 
librar
ii  octave-sp      2003-2         Semidefinite Programming functions for 
GNU O
ii  octave-statdat 1.0.9-1        GNU Octave package for XML-based data 
exchan
ii  octave2.1      2.1.69-1       GNU Octave language for numerical 
computatio
ii  octave2.1-doc  2.1.69-1       PDF documentation on the GNU Octave 
language
ii  octave2.1-head 2.1.69-1       header files for the GNU Octave language 
(2.
ii  octave2.1-html 2.1.69-1       HTML documentation on the GNU Octave 
languag

When I want plot function acot (inverse cotangent)

fplot('acot(x)',[-10,10])

I see, that I have wrong graph.

Mistake is in file
/usr/share/octave/2.1.69/m/elfun/acot.m

where is function acot defined by formula:

function w = acot (z)

   if (nargin != 1)
     usage ("acot (z)");
   endif

   w = atan (1./z);

endfunction





Right formula is

function w = acot (z)

   if (nargin != 1)
     usage ("acot (z)");
   endif

   w = pi/2 - atan (z);

endfunction

I download octave from http://www.octave.org/download.html

In version 2.0.17 is right formula and in version 2.1.72 and 2.9.4 is 
wrong version of file acot.m. I submit this bug to bug at octave.org and I 
hope, that new version of octave will have right version of this file.

You make package from version 2.1.69 which contains bad file acot.m.
Can you replace this file in package for sarge?

Jakub Stryja