+
−## 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 = 0.002, fmt = "")
+
−
+
−  if (nargin < 2 || nargin > 4)
+
−    print_usage ();
+
−  endif
+
−
+
−  if (iscomplex (limits) || (numel (limits) != 2 && numel (limits) != 4))
+
−    error ("fplot: LIMITS must be a real vector with 2 or 4 elements");
+
−  endif
+
−
+
−  if (ischar (n))
+
−    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: FN must be a function handle, inline function, or string");
+
−  endif
+
−
+
−  if (n != fix (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 || err < 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
+
−
+
−  plot (x, y, fmt);
+
−
+
−  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]);
+
−