function f = Hermite(x,y,y_1,x0)
syms t;
f = 0.0;

if(length(x) == length(y))
    if(length(y) == length(y_1))
        n = length(x);
    else
        disp('y和y的導數(shù)的維數(shù)不相等！');
        return;
    end
else
    disp('x和y的維數(shù)不相等！');
    return;
end

for i=1:n
    h = 1.0;
    a = 0.0;
    for j=1:n
        if( j ~= i)
            h = h*(t-x(j))^2/((x(i)-x(j))^2);
            a = a + 1/(x(i)-x(j));
        end
    end
    
    f = f + h*((x(i)-t)*(2*a*y(i)-y_1(i))+y(i));
    
    if(i==n)
        if(nargin == 4)
            f = subs(f,'t',x0);
        else
            f = vpa(f,6);
        end
    end
end