tomwalters@0: function h=ellipse(ra,rb,ang,x0,y0,C,Nb)
tomwalters@0: % Ellipse adds ellipses to the current plot
tomwalters@0: %
tomwalters@0: % ELLIPSE(ra,rb,ang,x0,y0) adds an ellipse with semimajor axis of ra,
tomwalters@0: % a semimajor axis of radius rb, a semimajor axis of ang, centered at
tomwalters@0: % the point x0,y0.
tomwalters@0: %
tomwalters@0: % The length of ra, rb, and ang should be the same. 
tomwalters@0: % If ra is a vector of length L and x0,y0 scalars, L ellipses
tomwalters@0: % are added at point x0,y0.
tomwalters@0: % If ra is a scalar and x0,y0 vectors of length M, M ellipse are with the same 
tomwalters@0: % radii are added at the points x0,y0.
tomwalters@0: % If ra, x0, y0 are vectors of the same length L=M, M ellipses are added.
tomwalters@0: % If ra is a vector of length L and x0, y0 are  vectors of length
tomwalters@0: % M~=L, L*M ellipses are added, at each point x0,y0, L ellipses of radius ra.
tomwalters@0: %
tomwalters@0: % ELLIPSE(ra,rb,ang,x0,y0,C)
tomwalters@0: % adds ellipses of color C. C may be a string ('r','b',...) or the RGB value. 
tomwalters@0: % If no color is specified, it makes automatic use of the colors specified by 
tomwalters@0: % the axes ColorOrder property. For several circles C may be a vector.
tomwalters@0: %
tomwalters@0: % ELLIPSE(ra,rb,ang,x0,y0,C,Nb), Nb specifies the number of points
tomwalters@0: % used to draw the ellipse. The default value is 300. Nb may be used
tomwalters@0: % for each ellipse individually.
tomwalters@0: %
tomwalters@0: % h=ELLIPSE(...) returns the handles to the ellipses.
tomwalters@0: %
tomwalters@0: % as a sample of how ellipse works, the following produces a red ellipse
tomwalters@0: % tipped up at a 45 deg axis from the x axis
tomwalters@0: % ellipse(1,2,pi/8,1,1,'r')
tomwalters@0: %
tomwalters@0: % note that if ra=rb, ELLIPSE plots a circle
tomwalters@0: %
tomwalters@0: 
tomwalters@0: % written by D.G. Long, Brigham Young University, based on the
tomwalters@0: % CIRCLES.m original 
tomwalters@0: % written by Peter Blattner, Institute of Microtechnology, University of 
tomwalters@0: % Neuchatel, Switzerland, blattner@imt.unine.ch
tomwalters@0: 
tomwalters@0: 
tomwalters@0: % Check the number of input arguments 
tomwalters@0: 
tomwalters@0: if nargin<1,
tomwalters@0:   ra=[];
tomwalters@0: end;
tomwalters@0: if nargin<2,
tomwalters@0:   rb=[];
tomwalters@0: end;
tomwalters@0: if nargin<3,
tomwalters@0:   ang=[];
tomwalters@0: end;
tomwalters@0: 
tomwalters@0: %if nargin==1,
tomwalters@0: %  error('Not enough arguments');
tomwalters@0: %end;
tomwalters@0: 
tomwalters@0: if nargin<5,
tomwalters@0:   x0=[];
tomwalters@0:   y0=[];
tomwalters@0: end;
tomwalters@0:  
tomwalters@0: if nargin<6,
tomwalters@0:   C=[];
tomwalters@0: end
tomwalters@0: 
tomwalters@0: if nargin<7,
tomwalters@0:   Nb=[];
tomwalters@0: end
tomwalters@0: 
tomwalters@0: % set up the default values
tomwalters@0: 
tomwalters@0: if isempty(ra),ra=1;end;
tomwalters@0: if isempty(rb),rb=1;end;
tomwalters@0: if isempty(ang),ang=0;end;
tomwalters@0: if isempty(x0),x0=0;end;
tomwalters@0: if isempty(y0),y0=0;end;
tomwalters@0: if isempty(Nb),Nb=300;end;
tomwalters@0: if isempty(C),C=get(gca,'colororder');end;
tomwalters@0: 
tomwalters@0: % work on the variable sizes
tomwalters@0: 
tomwalters@0: x0=x0(:);
tomwalters@0: y0=y0(:);
tomwalters@0: ra=ra(:);
tomwalters@0: rb=rb(:);
tomwalters@0: ang=ang(:);
tomwalters@0: Nb=Nb(:);
tomwalters@0: 
tomwalters@0: if isstr(C),C=C(:);end;
tomwalters@0: 
tomwalters@0: if length(ra)~=length(rb),
tomwalters@0:   error('length(ra)~=length(rb)');
tomwalters@0: end;
tomwalters@0: if length(x0)~=length(y0),
tomwalters@0:   error('length(x0)~=length(y0)');
tomwalters@0: end;
tomwalters@0: 
tomwalters@0: % how many inscribed elllipses are plotted
tomwalters@0: 
tomwalters@0: if length(ra)~=length(x0)
tomwalters@0:   maxk=length(ra)*length(x0);
tomwalters@0: else
tomwalters@0:   maxk=length(ra);
tomwalters@0: end;
tomwalters@0: 
tomwalters@0: % drawing loop
tomwalters@0: 
tomwalters@0: for k=1:maxk
tomwalters@0:   
tomwalters@0:   if length(x0)==1
tomwalters@0:     xpos=x0;
tomwalters@0:     ypos=y0;
tomwalters@0:     radm=ra(k);
tomwalters@0:     radn=rb(k);
tomwalters@0:     if length(ang)==1
tomwalters@0:       an=ang;
tomwalters@0:     else
tomwalters@0:       an=ang(k);
tomwalters@0:     end;
tomwalters@0:   elseif length(ra)==1
tomwalters@0:     xpos=x0(k);
tomwalters@0:     ypos=y0(k);
tomwalters@0:     radm=ra;
tomwalters@0:     radn=rb;
tomwalters@0:     an=ang;
tomwalters@0:   elseif length(x0)==length(ra)
tomwalters@0:     xpos=x0(k);
tomwalters@0:     ypos=y0(k);
tomwalters@0:     radm=ra(k);
tomwalters@0:     radn=rb(k);
tomwalters@0:     an=ang(k)
tomwalters@0:   else
tomwalters@0:     rada=ra(fix((k-1)/size(x0,1))+1);
tomwalters@0:     radb=rb(fix((k-1)/size(x0,1))+1);
tomwalters@0:     an=ang(fix((k-1)/size(x0,1))+1);
tomwalters@0:     xpos=x0(rem(k-1,size(x0,1))+1);
tomwalters@0:     ypos=y0(rem(k-1,size(y0,1))+1);
tomwalters@0:   end;
tomwalters@0: 
tomwalters@0:   co=cos(an);
tomwalters@0:   si=sin(an);
tomwalters@0:   the=linspace(0,2*pi,Nb(rem(k-1,size(Nb,1))+1,:)+1);
tomwalters@0: %  x=radm*cos(the)*co-si*radn*sin(the)+xpos;
tomwalters@0: %  y=radm*cos(the)*si+co*radn*sin(the)+ypos;
tomwalters@0:   h(k)=line(radm*cos(the)*co-si*radn*sin(the)+xpos,radm*cos(the)*si+co*radn*sin(the)+ypos);
tomwalters@0:   set(h(k),'color',C(rem(k-1,size(C,1))+1,:));
tomwalters@0: 
tomwalters@0: end;
tomwalters@0: