octave-bug-tracker
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Octave-bug-tracker] [bug #51963] test normpdf fails after __opengl_info


From: Dan Sebald
Subject: [Octave-bug-tracker] [bug #51963] test normpdf fails after __opengl_info__ using fltk on Intel graphics on Windows
Date: Fri, 8 Sep 2017 21:38:00 -0400 (EDT)
User-agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:54.0) Gecko/20100101 Firefox/54.0

Follow-up Comment #3, bug #51963 (project octave):

OK, so it's not sqrt() or exp() that is changing.

I think I see the difference in formulas.  It's in stdnormal_pdf.m where the
PDF values are computed.  In that routine, the formula is


pdf = (2 * pi)^(- 1/2) * exp (- x .^ 2 / 2);


while in the test in normpdf.m the formula for the comparison is


y = 1/sqrt(2*pi)*exp (-(x-1).^2/2);


So, my guess would be something with division then.  But let's try them all
again.  What result do you see for this:


[exit and relaunch Octave...]
y1 = (2 * pi)^(- 1/2);
y2 = 1/sqrt(2*pi);
y3 = exp(-1/2);
graphics_toolkit ("fltk");
__opengl_info__ ();
y4 = (2 * pi)^(- 1/2);
y5 = 1/sqrt(2*pi);
y6 = exp(-1/2);
y1 - y4
y2 - y5
y3 - y6
%



    _______________________________________________________

Reply to this item at:

  <http://savannah.gnu.org/bugs/?51963>

_______________________________________________
  Message sent via/by Savannah
  http://savannah.gnu.org/




reply via email to

[Prev in Thread] Current Thread [Next in Thread]