Figure 4 (page 7):

Histogram of 10,000 samples of {\sc Matlab}'s randn function.

Code for Figure 4

Text of the GNU GPL.

main.m

clear('all'); close('all');
x = randn(10000,1);
hist(x,50)

[nx, xsam] = hist(x, 50);
[xsamb, nxb] = obar(xsam, nx);

data = [xsamb, nxb];

save normhist.dat data

/export/home/jbraw/courses/cbe255/content/util/common/obar.m

% Copyright (C) 1996, 1997 John W. Eaton
%
% This file is part of Octave.
%
% Octave is free software; you can redistribute it and/or modify it
% under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2, or (at your option)
% any later version.
%
% Octave is distributed in the hope that it will be useful, but
% WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
% General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with Octave; see the file COPYING.  If not, write to the Free
% Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
% 02110-1301, USA.

% -*- texinfo -*-
% @deftypefn {Function File} {} bar (@var{x}, @var{y})
% Given two vectors of x-y data, @code{bar} produces a bar graph.
%
% If only one argument is given, it is taken as a vector of y-values
% and the x coordinates are taken to be the indices of the elements.
%
% If two output arguments are specified, the data are generated but
% not plotted.  For example,
%
% @example
% bar (x, y);
% @end example
%
% @noindent
% and
%
% @example
% [xb, yb] = bar (x, y);
% plot (xb, yb);
% @end example
%
% @noindent
% are equivalent.
% @end deftypefn
%
% @seealso{plot, semilogx, semilogy, loglog, polar, mesh, contour,
% stairs, replot, xlabel, ylabel, and title}

% Author: jwe

function [xb, yb] = obar (x, y)

  if (nargin == 1)
    if (isvector (x))
      len = 3 * length (x) + 1;
      tmp_xb = zeros (len, 1);
      tmp_yb = zeros (len, 1);
      tmp_xb(1) = 0.5;
      tmp_yb(1) = 0;
      k = 1;
      for i = 2:3:len
        tmp_xb(i) = k-0.5;
        tmp_xb(i+1) = k+0.5;
        tmp_xb(i+2) = k+0.5;
        tmp_yb(i) = x(k);
        tmp_yb(i+1) = x(k);
        tmp_yb(i+2) = 0.0;
        k=k+1;
      end
    else
      error ('bar: argument must be a vector');
    end
  elseif (nargin == 2)
    if (isvector (x) && isvector (y))
      xlen = length (x);
      ylen = length (y);
      if (xlen == ylen)
        len = 3 * xlen + 1;
        tmp_xb = zeros (len, 1);
        tmp_yb = zeros (len, 1);
        cutoff = zeros (1, xlen);
        for i = 1:xlen-1
          cutoff(i) = (x(i) + x(i+1)) / 2.0;
        end
        delta_p = cutoff(1) - x(1);
        delta_m = delta_p;
        tmp_xb(1) = x(1) - delta_m;
        tmp_yb(1) = 0.0;
        k = 1;
        for i = 2:3:len
          tmp_xb(i) = tmp_xb(i-1);
          tmp_xb(i+1) = x(k) + delta_p;
          tmp_xb(i+2) = tmp_xb(i+1);
          tmp_yb(i) = y(k);
          tmp_yb(i+1) = y(k);
          tmp_yb(i+2) = 0.0;
          if (k < xlen)
            if (x(k+1) < x(k))
              error ('bar: x vector values must be in ascending order');
            end
            delta_m = x(k+1) - cutoff(k);
            k=k+1;
            if (k < xlen)
              delta_p = cutoff(k) - x(k);
            else
              delta_p = delta_m;
            end
          end
        end
      else
        error ('bar: arguments must be the same length');
      end
    else
      error ('bar: arguments must be vectors');
    end
  else
    usage ('[xb, yb] = bar (x, y)');
  end

  if (nargout == 0)
    plot (tmp_xb, tmp_yb);
  else
    xb = tmp_xb;
    yb = tmp_yb;
  end