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[Octave-bug-tracker] [bug #49015] atan2 singular cases
From: |
Ernst Reissner |
Subject: |
[Octave-bug-tracker] [bug #49015] atan2 singular cases |
Date: |
Tue, 6 Sep 2016 13:49:28 +0000 (UTC) |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:48.0) Gecko/20100101 Firefox/48.0 |
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
_______________________________________________________
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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