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scripts/plot/cylinder.m

changeset 10289: 4b124317dc38
parent:1bf0ce0930be
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (62 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 2007, 2009 Michael Goffioul and Kai Habel

     2##

     3## This file is part of Octave.

     4##

     5## Octave is free software; you can redistribute it and/or modify it

     6## under the terms of the GNU General Public License as published by

     7## the Free Software Foundation; either version 3 of the License, or (at

     8## your option) any later version.

     9##

    10## Octave is distributed in the hope that it will be useful, but

    11## WITHOUT ANY WARRANTY; without even the implied warranty of

    12## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    13## General Public License for more details.

    14##

    15## You should have received a copy of the GNU General Public License

    16## along with Octave; see the file COPYING.  If not, see

    17## <http://www.gnu.org/licenses/>.

    18

    19## -*- texinfo -*-

    20## @deftypefn {Function File} {} cylinder

    21## @deftypefnx {Function File} {} cylinder (@var{r})

    22## @deftypefnx {Function File} {} cylinder (@var{r}, @var{n})

    23## @deftypefnx {Function File} {[@var{x}, @var{y}, @var{z}] =} cylinder (@dots{})

    24## @deftypefnx {Function File} {} cylinder (@var{ax}, @dots{})

    25## Generates three matrices in @code{meshgrid} format, such that

    26## @code{surf (@var{x}, @var{y}, @var{z})} generates a unit cylinder.

    27## The matrices are of size @code{@var{n}+1}-by-@code{@var{n}+1}. 

    28## @var{r} is a vector containing the radius along the z-axis.

    29## If @var{n} or @var{r} are omitted then default values of 20 or [1 1]

    30## are assumed.

    31##

    32## Called with no return arguments, @code{cylinder} calls directly

    33## @code{surf (@var{x}, @var{y}, @var{z})}.  If an axes handle @var{ax}

    34## is passed as the first argument, the surface is plotted to this set

    35## of axes.

    36##

    37## Examples:

    38## @example

    39## @group

    40## disp ("plotting a cone")

    41## [x, y, z] = cylinder (10:-1:0,50);

    42## surf (x, y, z);

    43## @end group

    44## @end example

    45## @seealso{sphere}

    46## @end deftypefn

    47

    48function [xx, yy, zz] = cylinder (varargin)

    49

    50  [ax, args, nargs] = __plt_get_axis_arg__ ((nargout > 0), "cylinder", 

    51					    varargin{:});

    52

    53  if (nargs == 0)

    54    n = 20;

    55    r = [1, 1];

    56  elseif (nargs == 1)

    57    n = 20;

    58    r = args{1};

    59  elseif (nargs == 2)

    60    r = args{1};

    61    n = args{2};

    62  else

    63    print_usage ();

    64  endif

    65

    66  if (length (r) < 2)

    67    error ("cylinder: length(r) must be larger than 2")

    68  endif

    69

    70  phi = linspace (0, 2*pi, n+1);

    71  idx = 1:length(r);

    72  [phi, idx] = meshgrid(phi, idx);

    73  z = (idx - 1) / (length(r) - 1);

    74  r = r(idx);

    75  [x, y] = pol2cart (phi, r);

    76

    77  if (nargout > 0)

    78    xx = x;

    79    yy = y;

    80    zz = z;

    81  else

    82    surf (ax, x, y, z);

    83  endif

    84

    85endfunction

    86

    87%!demo

    88%! disp ("plotting a cone")

    89%! [x, y, z] = cylinder (10:-1:0,50);

    90%! surf (x, y, z);