线性插值是指插值函数为一次多项式的插值方式，其在插值节点上的插值误差为零。线性插值相比其他插值方式，如抛物线插值，具有简单、方便的特点。线性插值的几何意义即为概述图中利用过A点和B点的直线来近似表示原函数。线性插值可以用来近似代替原函数，也可以用来计算得到查表过程中表中没有的数值。(Linear interpolation means interpolation function with polynomial interpolation, and its interpolation error is zero at interpolation nodes. Compared with other interpolation methods such as parabolic interpolation, linear interpolation is simple and convenient. The geometric meaning of linear interpolation means that the original function is approximated by using a straight line passing through A points and B points. Linear interpolation can be used to approximately replace the original function, and it can also be used to calculate the values that are not found in the table during the look-up table.)