function plot_capacitor(w,h,A,B)
%
%  plot_capacitor(w,h,A,B) plots a capacitor,
%  using width w and heigth h,
%  starting at position A and ending at B.
%
%  ON ENTRY:
%    w      width of the capacitor; 
%    h      height of the capacitor; 
%    A      x and y coordinates of start position;
%    B      x and y coordinates of end position.
%
%  EXAMPLE:
%    plot_capacitor(0.1,0.4,[1,1],[2,1])
%    axis([0 3 0 2])
%
x1 = [-1,-w];  y1 = [0,0];
x2 = [-w,-w];  y2 = [-h,h];
x3 = [w,w];    y3 = [-h,h];
x4 = [w,1];    y4 = [0,0];
if (ishold == 0) 
   hold on;
end;
[xx1,yy1] = coordinate_transformation(x1,y1,A,B);
[xx2,yy2] = coordinate_transformation(x2,y2,A,B);
[xx3,yy3] = coordinate_transformation(x3,y3,A,B);
[xx4,yy4] = coordinate_transformation(x4,y4,A,B);
plot(xx1,yy1);
plot(xx2,yy2);
plot(xx3,yy3);
plot(xx4,yy4);