用matlab编程求搅拌车的搅动容积求助，用书上给出的程序，输进去，求出来的是y2的值，怎么才能求出搅动容积V的值呢，请大家帮忙看看：
>> clear
   V0=10;
   a0=8;
   a1=15;
   a2=22.5;
   c1=1.8;
   c2=0.97;
   y0=0.3;
   e=0.5;
   w=2.49;
   s=0.05;
   %
   y2=1;
   V=8;
   %
   while abs (V-V0)>e
          L1=1.8*y2;
          L2=(16.6-1.68*pi*y2^3)/pi/y2^2;
          L3=0.97*y2;
          y1=0.5*y2;
          y3=0.6*y2;
          Y1=sym('0.27777*x+0.5*y2');
          Y2=y2;
          Y3=sym('0.4124*(2.545*pi*y2^3+16.6-x*pi*y2^2)/pi/y2^2');
          Y4=sym('0.3-0.14*x');
   F1=sym('0.5*((0.2777*x+0.5*y2)^2)*acos((0.3-0.14*x)/(x/3.6+0.5*y2))-0.5*(0.3-0.14*x)*sqrt(0.05756*x^2+0.25*y2^2-0.09+0.0504*x+0.27777*x*y2)');
   F21=sym('0.5*y2^2*acos((0.3-0.14*x)/y2)-0.5*(0.3-0.14*x)*sqrt(y2^2-0.09+0.084*x-0.0196*x^2)');
   F22=sym('0.5*y2^2*(2*pi-acos((0.14*x-0.3)/y2))+0.5*(0.14*x-0.3)*sqrt(y2^2-0.09+0.084*x-0.0196*x^2)');
   F3=sym('0.17*(2.545*pi*(y2^3)+16.6-x*pi*(y2^2))^2/pi^2/y2^4*pi-0.085*(2.545*pi*y2^3+16.6-x*pi*y2^2)^2/pi^2/y2^4*(acos((0.14*x-0.3)*2.425*pi*y2^2/(2.545*pi*(y2^3)+16.6-x*pi*(y2^2))))+0.5*(0.14*x-0.3)*sqrt(0.17*(2.545*pi*(y2^3)+16.6-x*pi*y2^2)^2/pi^2/y2^4-0.09+0.084*x-0.0196*x^2)');
   %
          V1=int(F1,0,L1);
          V21=int(F21,L1,0.3/0.14);
          V22=int(F22,0.3/0.14,L1+L2);
          V3=int(F3,L1+L2,L1+L2+L3);
          V4=V1+V21+V22+V3;
          V=subs(V4,'y2',y2);          %料体积计算
   %
      if    Y2<w
             if V-V0>0
                 y2=y2+s
             else
                 y2=y2-s
             end
            else
            y2=y2-s
            end
     end