update packages

[CreaPhase.git] / octave_packages / m / plot / fplot.m

diff --git a/octave_packages/m/plot/fplot.m b/octave_packages/m/plot/fplot.m
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+## Copyright (C) 2005-2012 Paul Kienzle
+##
+## 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 3 of the License, 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, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn  {Function File} {} fplot (@var{fn}, @var{limits})
+## @deftypefnx {Function File} {} fplot (@var{fn}, @var{limits}, @var{tol})
+## @deftypefnx {Function File} {} fplot (@var{fn}, @var{limits}, @var{n})
+## @deftypefnx {Function File} {} fplot (@dots{}, @var{fmt})
+## Plot a function @var{fn} within defined limits.
+## @var{fn} is a function handle, inline function, or string
+## containing the name of the function to evaluate.
+## The limits of the plot are given by @var{limits} of the form
+## @code{[@var{xlo}, @var{xhi}]} or @code{[@var{xlo}, @var{xhi},
+## @var{ylo}, @var{yhi}]}.  @var{tol} is the default tolerance to use for the
+## plot, and if @var{tol} is an integer it is assumed that it defines the
+## number points to use in the plot.  The @var{fmt} argument is passed
+## to the plot command.
+##
+## @example
+## @group
+## fplot ("cos", [0, 2*pi])
+## fplot ("[cos(x), sin(x)]", [0, 2*pi])
+## @end group
+## @end example
+## @seealso{plot}
+## @end deftypefn
+
+## Author: Paul Kienzle <pkienzle@users.sf.net>
+
+function fplot (fn, limits, n, fmt)
+  if (nargin < 2 || nargin > 4)
+    print_usage ();
+  endif
+
+  if (!isreal (limits) || (numel (limits) != 2 && numel (limits) != 4))
+    error ("fplot: second input argument must be a real vector with 2 or 4 elements");
+  endif
+
+  if (nargin < 3)
+    n = 0.002;
+  endif
+
+  have_linespec = true;
+  if (nargin < 4)
+    have_linespec = false;
+  endif
+
+  if (ischar (n))
+    have_linespec = true;
+    fmt = n;
+    n = 0.002;
+  endif
+
+  if (strcmp (typeinfo (fn), "inline function"))
+    fn = vectorize (fn);
+    nam = formula (fn);
+  elseif (isa (fn, "function_handle"))
+    nam = func2str (fn);
+  elseif (all (isalnum (fn)))
+    nam = fn;
+  elseif (ischar (fn))
+     fn = vectorize (inline (fn));
+     nam = formula (fn);
+  else
+    error ("fplot: first input argument must be a function handle, inline function or string");
+  endif
+
+  if (floor(n) != n)
+    tol = n;
+    x0 = linspace (limits(1), limits(2), 5)';
+    y0 = feval (fn, x0);
+    err0 = Inf;
+    n = 8;
+    x = linspace (limits(1), limits(2), n)';
+    y = feval (fn, x);
+
+    while (n < 2 .^ 20)
+      y00 = interp1 (x0, y0, x, "linear");
+      err = 0.5 * max (abs ((y00 - y) ./ (y00 + y))(:));
+      if (err == err0 || 0.5 * max (abs ((y00 - y) ./ (y00 + y))(:)) < tol)
+        break;
+      endif
+      x0 = x;
+      y0 = y;
+      err0 = err;
+      n = 2 * (n - 1) + 1;
+      x = linspace (limits(1), limits(2), n)';
+      y = feval (fn, x);
+    endwhile
+  else
+    x = linspace (limits(1), limits(2), n)';
+    y = feval (fn, x);
+  endif
+
+  if (have_linespec)
+    plot (x, y, fmt);
+  else
+    plot (x, y);
+  endif
+
+  if (length (limits) > 2)
+    axis (limits);
+  endif
+
+  if (isvector (y))
+    legend (nam);
+  else
+    for i = 1:columns (y)
+      nams{i} = sprintf ("%s(:,%i)", nam, i);
+    endfor
+    legend (nams{:});
+  endif
+endfunction
+
+%!demo
+%! clf
+%! fplot ("cos", [0, 2*pi])
+
+%!demo
+%! clf
+%! fplot ("[cos(x), sin(x)]", [0, 2*pi])