int2cir.m

在matlab环境下

  function y = int2cir(r1,r2,a,b)
  % intersection points of 2 circles
  % (0,0) origin of 1-circle;
  % (a,b) origin of 2-circle
  %  r1 -  1-circle radius
  %  r2 -  2-circle radius
  %  (y(1),y(2)) - (x,y) first choice
  %  (y(3),y(4)) - (x,y) second chice  
           k = -0.5*(r2^2-r1^2-a^2-b^2);
           k1 = a^2+b^2;
           k2 = -2*k*b;
           k3 = k^2-a^2*r1^2;
           yy = sqrt(k2^2-4*k1*k3);
           if imag(yy) ~= 0
            disp(' the link-lengths are very small')   
            error(' increase the link lengths')
        else
           y1 = (-k2+yy)/(2*k1);
           y2 = (-k2-yy)/(2*k1);
           x1 = (k-b*y1)/a;
           x2 = (k-b*y2)/a;
           y(1) = x1;
           y(2) = y1;
           y(3) = x2;
           y(4) = y2;
           y = y';
       end;