定义1设函数f(x)(x∈I,I是区间),a∈I,区间I_-={x|x∈I且x≤a},I_+={x|x∈I且x≥a}.(1)若f(x)在I_-,I_+上分别是减函数、增函数,则称f(x)是V型函数(也叫做单谷函数);(2)若f(x)在I_-,I_+上分别是增函数、减函数,则称f(x)是Λ型函数(也叫做单峰函数);(3)把单谷函数和单峰函数统称为单极函数(显然,单极函数有唯一的极值点). Definition 1 Let the function f (x) (x∈I, I be the interval), a∈I, the interval I _- ​​= {x | x∈I and x≤a}, I_ + = {x | x∈I and x≥ (1) If f (x) is a decreasing function on I_- and I_ +, then f (x) is a V-shaped function (also called a single-valley function) (x) is an Λ-type function (also called unimodal function); (3) the single-valley function and the unimodal function are collectively referred to as unipolar Function (obviously, the unipolar function has a unique extreme point).