# HG changeset patch
# User jwe
# Date 780176554 0
# Node ID 86d73993eee286fe2f09c6a81b1e2f6d9263e468
# Parent  1c072f20b522e6256dc7a04ef0b315ecf9d2892b
[project @ 1994-09-21 19:42:34 by jwe]
Initial revision

diff --git a/scripts/plot/hist.m b/scripts/plot/hist.m
new file mode 100644
--- /dev/null
+++ b/scripts/plot/hist.m
@@ -0,0 +1,107 @@
+# Copyright (C) 1994 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, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+function [nn, xx] = hist (y, x)
+
+# usage: [NN, XX] = hist (Y, X)  or  hist (Y, X)
+#
+# Produce histogram counts or plots.
+#
+# With one vector input argument, plot a histogram of the values with
+# 10 bins.  The range of the histogram bins is determined by the range
+# of the data.
+#
+# Given a second scalar argument, use that as the number of bins.
+#
+# Given a second vector argument, use that as the centers of the bins,
+# with the width of the bins determened from the adjacent values in
+# the vector.
+#
+# Extreme values are lumped in the first and last bins.
+#
+# With two output arguments, produce the values NN and XX such that
+# bar (XX, NN) will plot the histogram.
+#
+# See also: bar
+
+  if (nargin < 1 || nargin > 2)
+    error ("usage: [nn, xx] = hist (y, x)");
+  endif
+    
+  if (is_vector (y))
+    max_val = max (y);
+    min_val = min (y);
+  else
+    error ("hist: first argument must be a vector");
+  endif
+
+  if (nargin == 1)
+    n = 10;
+    delta = (max_val - min_val) / n / 2;
+    x = linspace (min_val+delta, max_val-delta, n);
+    cutoff = x + delta;
+  elseif (nargin == 2)
+    if (is_scalar (x))
+      n = x;
+      if (n <= 0)
+        error ("hist: number of bins must be positive");
+      endif
+      delta = (max_val - min_val) / n / 2;
+      x = linspace (min_val+delta, max_val-delta, n);
+      cutoff = x + delta;
+    elseif (is_vector (x))
+      tmp = sort (x);
+      if (any (tmp != x))
+        fprintf (stderr, "warning: hist: bin values not sorted on input\n");
+        x = tmp;
+      endif
+      n = length (x);
+      cutoff = zeros (1, n-1);
+      for i = 1:n-1
+        cutoff (i) = (x (i) + x (i+1)) / 2;
+      endfor
+    else
+      error ("hist: second argument must be a scalar or a vector");
+    endif
+  endif
+
+  freq = zeros (1, n);
+  freq (1) = sum (y < cutoff (1));
+  for i = 2:n-1
+    freq (i) = sum (y >= cutoff (i-1) & y < cutoff (i));
+  endfor
+  freq (n) = sum (y >= cutoff (n-1));
+
+# With Octave 1.0, nargout is never zero, so we have to do this: 
+
+  nn = freq;
+  xx = x;
+  if (nargout != 2)
+    bar (xx, nn);
+  endif
+
+# Once 1.1 is released, we can do this instead:
+#
+#  if (nargout == 2)
+#    nn = freq;
+#    xx = x;
+#  else
+#    bar (x, freq);
+#  endif
+
+endfunction