功能：用斐波那契法求f(x)在区间[a,b]上的近似极小值。当且仅当f(x)在[a,b]上为单峰时次方法适用-Function: The Fibonacci method f (x) in the interval [a, b] on the approximate minimum. If and only if f (x) in [a, b] for the single-peak method can be applied at times