circle.m

Matlab中的画圆函数。Matlab本身没有画圆的函数。本附件实现了画圆函数。

function h=circle(r,x0,y0,C,Nb)

% CIRCLE adds circles to the current plot
%
% CIRCLE(r,x0,y0) adds a circle of radius r centered at point x0,y0.
% If r is a vector of length L and x0,y0 scalars, L circles with radii r
% are added at point x0,y0.

% If r is a scalar and x0,y0 vectors of length M, M circles are with the same
% radius r are added at the points x0,y0.

% If r, x0,y0 are vector of the same length L=M, M circles are added. (At each
% point one circle).

% if r is a vector of length L and x0,y0 vectors of length M~=L, L*M circles are
% added, at each point x0,y0, L circles of radius r.
%
% CIRCLE(r,x0,y0,C)

% adds circles of color C. C may be a string ('r','b',...) or the RGB value.
% If no color is specified, it makes automatic use of the colors specified by
% the axes ColorOrder property. For several circles C may be a vector.
%
% CIRCLE(r,x0,y0,C,Nb), Nb specifies the number of points used to draw the
% circle. The default value is 300. Nb may be used for each circle individually.
%
% h=CIRCLE(...) returns the handles to the circles.
%
% Try out the following (nice) examples:
%
%% Example 1
%
% clf;
% x=zeros(1,200);
% y=cos(linspace(0,1,200)*4*pi);
% rad=linspace(1,0,200);
% cmap=hot(50);
% circle(rad,x,y,[flipud(cmap);cmap]);
%
%% Example 2
%
% clf;
% the=linspace(0,pi,200);
% r=cos(5*the);
% circle(0.1,r.*sin(the),r.*cos(the),hsv(40));
%
%
%% Example 3
%
% clf
% [x,y]=meshdom(1:10,1:10);
% circle([0.5,0.3,0.1],x,y,['r';'y']);
%
%% Example 4
%
% clf
% circle(1:10,0,0,[],3:12);
%
%% Example 5
%
% clf;
% circle((1:10),[0,0,20,20],[0,20,20,0]);
% rewritten by Din-sue Fon. Dept. of Bio-Industrial Mechatronics Engineering,
% National Taiwan University March 10,2001
% [e-mail]
% written by Peter Blattner, Institute of Microtechnology, University of
% Neuchatel, Switzerland, [e-mail]
axis equal;
% hold on;
% grid on;
% Check the number of input arguments

switch nargin
case 0
   r=[];x0=[];y0=[];C=[];Nb=[];
case 1
   x0=[];y0=[];C=[];Nb=[];
case 2
   y0=zeros(1,length(x0));C=[];Nb=[];
case 3
   C=[];Nb=[];
case 4
   Nb=[];
end

if length(x0)~=length(y0),
   if length(y0)==1,
      y0=ones(1,length(x0))*y0;
  elseif length(x0)==1,
      x0=ones(1,length(y0))*x0;
  else
      error('The lengths of x0 and y0 must be identical');
  end;
end;

% set up the default values
if isempty(r),r=1;end;
if isempty(x0),x0=0;end;
if isempty(y0),y0=0;end;
if isempty(Nb),Nb=300;end;
if isempty(C),C=get(gca,'colororder');end;
if isstr(C),C=C(:);end;
% work on the variable sizes
x0=x0(:);
y0=y0(:);
r=r(:);
Nb=Nb(:);
% how many rings are plottet
  if length(r)~=length(x0)
  maxk=length(r)*length(x0);
else
  maxk=length(r);
end;
route=0;
if length(x0)==1, route=1; end
if length(r)==1, route=2; end
if length(x0)==length(r), route=3; end

% drawing loop
for k=1:maxk
  switch route
      case 1
    xpos=x0;
    ypos=y0;
    rad=r(k);
case 2
    xpos=x0(k);
    ypos=y0(k);
    rad=r;
case 3
    xpos=x0(k);
    ypos=y0(k);
    rad=r(k);
otherwise
    rad=r(fix((k-1)/size(x0,1))+1);
    xpos=x0(rem(k-1,size(x0,1))+1);
    ypos=y0(rem(k-1,size(y0,1))+1);
end; % for switch
   theta=linspace(0,2*pi,Nb(rem(k-1,size(Nb,1))+1,:)+1);
  h(k)=line(rad*cos(theta)+xpos,rad*sin(theta)+ypos);
  set(h(k),'color',C(rem(k-1,size(C,1))+1,:));
end;