Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / control-2.3.52 / __axis_limits__.m

diff --git a/octave_packages/control-2.3.52/__axis_limits__.m b/octave_packages/control-2.3.52/__axis_limits__.m
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+## Copyright (C) 1998, 2000, 2004, 2005, 2007
+##               Auburn University.  All rights reserved.
+##
+##
+## This program 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 3 of the License, or (at
+## your option) any later version.
+##
+## This program 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 this program; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} __axis_limits__ (@var{axdata})
+## Determine axis limits for 2-D data (column vectors); leaves a 10%
+## margin around the plots.
+## Inserts margins of +/- 0.1 if data is one-dimensional 
+## (or a single point).
+##
+## @strong{Input}
+## @table @var
+## @item axdata
+## @var{n} by 2 matrix of data [@var{x}, @var{y}].
+## @end table
+##
+## @strong{Output}
+## @table @var
+## @item axvec
+## Vector of axis limits appropriate for call to @command{axis} function.
+## @end table
+## @end deftypefn
+
+function axvec = __axis_limits__ (axdata)
+
+  if (nargin < 1 || isempty (axdata))
+    axdata = 0;
+  endif
+
+  ## compute axis limits
+  minv = min (axdata);
+  maxv = max (axdata);
+  delv = (maxv-minv)/2;             # breadth of the plot
+  midv = (minv + maxv)/2;           # midpoint of the plot
+  axmid = [midv(1), midv(1), midv(2), midv(2)];
+  axdel = [-0.1, 0.1, -0.1, 0.1];   # default plot width (if less than 2-d data)
+  if (max (delv) == 0)
+    if (midv(1) != 0)
+      axdel(1:2) = [-0.1*midv(1), 0.1*midv(1)];
+    endif
+    if (midv(2) != 0)
+      axdel(3:4) = [-0.1*midv(2), 0.1*midv(2)];
+    endif
+  else
+    ## they're at least one-dimensional
+    tolv = max(1e-8, 1e-8*abs(midv));
+    if (abs (delv(1)) >= tolv(1))
+      axdel(1:2) = 1.1*[-delv(1),delv(1)];
+    endif
+    if (abs (delv(2)) >= tolv(2))
+      axdel(3:4) = 1.1*[-delv(2),delv(2)];
+    endif
+  endif
+  axvec = axmid + axdel;
+
+endfunction