ellipse.m

MATLAB中画椭圆的自定义函数：ellipse

function h=ellipse(ra,rb,ang,x0,y0,C,Nb) 
% Ellipse adds ellipses to the current plot 
% 
% ELLIPSE(ra,rb,ang,x0,y0) adds an ellipse with semimajor axis of ra, 
% a semimajor axis of radius rb, a semimajor axis of ang, centered at 
% the point x0,y0. 
% 
% The length of ra, rb, and ang should be the same. 
% If ra is a vector of length L and x0,y0 scalars, L ellipses 
% are added at point x0,y0. 
% If ra is a scalar and x0,y0 vectors of length M, M ellipse are with the same 
% radii are added at the points x0,y0. 
% If ra, x0, y0 are vectors of the same length L=M, M ellipses are added. 
% If ra is a vector of length L and x0, y0 are  vectors of length 
% M~=L, L*M ellipses are added, at each point x0,y0, L ellipses of radius ra. 
% 
% ELLIPSE(ra,rb,ang,x0,y0,C) 
% adds ellipses 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. 
% 
% ELLIPSE(ra,rb,ang,x0,y0,C,Nb), Nb specifies the number of points 
% used to draw the ellipse. The default value is 300. Nb may be used 
% for each ellipse individually. 
% 
% h=ELLIPSE(...) returns the handles to the ellipses. 
% 
% as a sample of how ellipse works, the following produces a red ellipse 
% tipped up at a 45 deg axis from the x axis 
% ellipse(1,2,pi/8,1,1,'r') 
% 
% note that if ra=rb, ELLIPSE plots a circle 
% 
% rewritten by Din-sue Fon. Dept. of Bio-Industrial Mechatronics Engineering, 
% National Taiwan University March 10,2001 
% [e-mail] 
% % rewritten by Din-sue Fon. Dept. of Bio-Industrial Mechatronics Engineering, 
% National Taiwan University March 10,2001 
% [e-mail] 
% written by D.G. Long, Brigham Young University, based on the 
% CIRCLES.m original 
% written by Peter Blattner, Institute of Microtechnology, University of 
% Neuchatel, Switzerland, [e-mail] 
  % Check the number of input arguments 
switch nargin 
case 0 
   ra=1;rb=1;ang=0;x0=0;y0=0;C=[];Nb=300; 
case 1 
   rb=ra;ang=0;x0=0;y0=0;C=[];Nb=300; 
case 2 
   ang=0;x0=0;y0=0;C=[];Nb=300; 
case 3 
   x0=0;y0=0;C=[];Nb=300; 
case 4 
   y0=zeros(1,length(x0));C=[];Nb=300; 
case 5 
   C=[];Nb=300; 
case 6 
   Nb=300; 
end 
  
 % set up the default values 
 if isempty(ra),ra=1;end; 
if isempty(rb),rb=1;end; 
if isempty(ang),ang=0;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; 
 % work on the variable sizes 
 x0=x0(:); 
y0=y0(:); 
ra=ra(:); 
rb=rb(:); 
ang=ang(:); 
Nb=Nb(:); 
 if isstr(C),C=C(:);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; if length(ra)~=length(rb), 
   if length(ra)==1, 
      ra=ones(1,length(rb))*ra; 
   elseif length(x0)==1, 
      rb=ones(1,length(ra))*rb; 
   else 
      error('The lengths of ra and rb must be identical'); 
   end; 
end;   % how many inscribed elllipses are plotted 
 if length(ra)~=length(x0) 
  maxk=length(ra)*length(x0); 
else 
  maxk=length(ra); 
end; 
    % drawing loop 
route=0; 
if length(x0)==1, route=1; end 
if length(ra)==1, route=2; end 
if length(x0)==length(ra), route=3; end 
if length(ang)>1 & length(ra)==1, 
   route=4;maxk=length(ang); 
end 
 for k=1:maxk 
  switch route 
  case 1 
    xpos=x0; 
    ypos=y0; 
    radm=ra(k); 
    radn=rb(k); 
    if length(ang)==1, an=ang; else an=ang(k); end; 
  case 2 
    xpos=x0(k); 
    ypos=y0(k); 
    radm=ra; 
    radn=rb; 
    if length(ang)==1, an=ang; else an=ang(k); end; 
  case 3 
    xpos=x0(k); 
    ypos=y0(k); 
    radm=ra(k); 
    radn=rb(k); 
    if length(ang)==1, an=ang; else an=ang(k); end; 
  case 4 
    xpos=x0; 
    ypos=y0; 
    radm=ra; 
    radn=rb; 
    an=ang(k); 
  otherwise 
    rada=ra(fix((k-1)/size(x0,1))+1); 
    radb=rb(fix((k-1)/size(x0,1))+1); 
    an=ang(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; 
   co=cos(an); 
  si=sin(an); 
  the=linspace(0,2*pi,Nb(rem(k-1,size(Nb,1))+1,:)+1); 
%  x=radm*cos(the)*co-si*radn*sin(the)+xpos; 
%  y=radm*cos(the)*si+co*radn*sin(the)+ypos; 
  h(k)=line(radm*cos(the)*co-si*radn*sin(the)+xpos,radm*cos(the)*si+co*radn*sin(the)+ypos); 
  set(h(k),'color',C(rem(k-1,size(C,1))+1,:)); 
 end; 
axis equal;grid on;