无法从 sym 转换为 logical 出错 fminbnd (第 335 行) if fu <= fx ，怎么解决？

t=readtable(app.InitialflowEditField.Value)
a=0.5
b=4
v=0.7

        F=0 
        syms y
        for i=1:app.roadnumberEditField.Value
            f(i)=(t.t0(i)-t.c(i))*y+(a*(t.c0(i)))*(t.t0(i))/(b+1)*(y/(t.c0(i)))^(b+1)-(t.t0(i)-t.c(i))*(t.x(i))-(a*(t.c0(i)))*(t.t0(i))/(b+1)*(t.x(i)/(t.c0(i)))^(b+1)
            F=F+f(i)
        end
        [y,fval]=fminbnd(@(y)v*(t.c(1))*y+(1-v)*F,0,1.0E+37)