[Octave-bug-tracker] [bug #49015] atan2 singular cases

[Ernst Reissner]

URL:
  <http://savannah.gnu.org/bugs/?49015>

                 Summary: atan2 singular cases
                 Project: GNU Octave
            Submitted by: ernstreissner
            Submitted on: Tue 06 Sep 2016 01:49:26 PM GMT
                Category: None
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: None
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: Any

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Details:

i doubt that atan2(y,x) is nothing but atan(y/x). 
I think the truth is 

%% This is essentially @code{atan(y/z)} with the following exceptions: 
%% @itemize
%% @item
%% If the first argument is @code{+0} and the second argument is negative, 
%% or the first argument is positive and finite 
%% and the second argument is negative infinity, 
%% then the result is the highest value less or equal to @code{pi}. 
%% @item
%% If the first argument is @code{-0} and the second argument is negative, 
%% or the first argument is negative and finite 
%% and the second argument is negative infinity, 
%% then the result is the lowest value less or equal to @code{-pi}.
%% @item
%% If the first argument is positive and the second argument is @code{0}, 
%% or the first argument is positive infinity 
%% and the second argument is finite, 
%% then the result is the double value closest to @code{pi/2}. 
%% @item
%% If the first argument is negative and the second argument is @code{0}, 
%% or the first argument is negative infinity 
%% and the second argument is finite, 
%% then the result is the double value closest to @code{-pi/2}. 
%% @item
%% If both arguments are positive infinity, 
%% then the result is the value closest to @code{pi/4}.
%% @item
%% If the first argument is positive infinity 
%% and the second argument is negative infinity, 
%% then the result is the double value closest to @code{3*pi/4}.
%% @item
%% If the first argument is negative infinity and 
%% the second argument is positive infinity, 
%% then the result is the double value closest to @code{-pi/4}.
%% @item
%% If both arguments are negative infinity, 
%% then the result is the double value closest to @code{-3*pi/4}.
%% @end itemize
%%




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