代码出错调试

m=2;
rows=3;
columns=3;
s=primpoly(m);%产生不可约多项式（本源多项式）
while 1
    u=randi([0,2^m-1],rows,columns);
    t=randi([0,2^m-1],rows,columns);
    U=gf(u,m,s);
    rank_u=rank(u);
    rank_t=rank(t);
    if (rank_u==rows)&&(rank_t==rows)
       break;
    else
        continue;
    end
end
syms x1 x2 x3 y real
X=[x1 x2 x3]';
Y=[1,y,y^2];
Y_16=[1,y^2,y^2+y];
v=randi([0,2^m-1],rows,1);
U_X=U*X+v  %本行出错





出错提示：Error using mupadmex
Error in MuPAD command: DOUBLE cannot convert the input expression into a double array.

If the input expression contains a symbolic variable, use the VPA function instead.

Error in sym/double (line 702)
        Xstr = mupadmex('symobj::double', S.s, 0);

Error in gf (line 40)
    if  ~all(all(isfinite(double(x))))

Error in gf/mtimes (line 12)
if ~isa(y,'gf'), y = gf(y,x.m,x.prim_poly); end

Error in matrix_combine (line 4)
s=A*B;

Error in test (line 22)
U_X=matrix_combine(U,X)+v

小弟刚接触Matlab  求高手指点一下 我这个该怎样改一下才行，感激不尽