[Octave-bug-tracker] [bug #41819] Plot function misdraws plots given an 'x' in plot fmt argument.

[Allan Jacobs]

URL:
  <http://savannah.gnu.org/bugs/?41819>

                 Summary: Plot function misdraws plots given  an 'x' in plot
fmt argument.
                 Project: GNU Octave
            Submitted by: allanjacobs
            Submitted on: Mon 10 Mar 2014 12:20:57 AM GMT
                Category: Plotting with OpenGL
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Regression
                  Status: None
             Assigned to: None
         Originator Name: allanjacobs
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

$ octave --version
GNU Octave, version 4.1.0+

Source code pulled, compiled, and installed on March 9, 2014.  The input data
and a screenshot are attached.  I'll attach a screenshot using 3.6.4 later.

Changing the fmt from 'rx' to 'ro' yields a plot which looks correct.  The
badness with 'rx' stems from drawing the back stroke of the 'X' ('') in a
position different from the forward stroke ('/').

function plotData(x, y)
%PLOTDATA Plots the data points x and y into a new figure 
%   PLOTDATA(x,y) plots the data points and gives the figure axes labels of
%   population and profit.
% ====================== YOUR CODE HERE ======================
% Instructions: Plot the training data into a figure using the 
%               "figure" and "plot" commands. Set the axes labels using
%               the "xlabel" and "ylabel" commands. Assume the 
%               population and revenue data have been passed in
%               as the x and y arguments of this function.
%
% Hint: You can use the 'rx' option with plot to have the markers
%       appear as red crosses. Furthermore, you can make the
%       markers larger by using plot(..., 'rx', 'MarkerSize', 10);
figure; % open a new figure window
plot(x, y, 'rx', 'MarkerSize', 10);         % Plot the data
ylabel('Profit in $10,000s');               % Set the y-axis label
xlabel('Population of City in 10,000s');    % Set the x-axis label
% ============================================================
end
data = load('ex1data1.txt');
X = data(:, 1); y = data(:, 2);
m = length(y); % number of training examples
plotData(X, y);





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File Attachments:


-------------------------------------------------------
Date: Mon 10 Mar 2014 12:20:57 AM GMT  Name: ex1data1.txt  Size: 1kB   By:
allanjacobs

<http://savannah.gnu.org/bugs/download.php?file_id=30839>
-------------------------------------------------------
Date: Mon 10 Mar 2014 12:20:57 AM GMT  Name: badx.png  Size: 15kB   By:
allanjacobs

<http://savannah.gnu.org/bugs/download.php?file_id=30840>

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