使用线性方程组求系数构造插值公式相对复杂，可改用构造方法来插值。

对节点xi(i=0,1,…,n)中任一点xk(0<=k<=n)作一n 次多项式lk(xk)，使它在该点上取值为1，而在其余点xi(i=0,1,…,k-1,k+1,…,n)上为0，则插值多项式为Ln(x)=y0l0(x)+y1l1(x)+y2l2(x)+…+ynln(x)

上式表明：n 个点xi(i=0,1,…,k-1,k+1,…,n)都是lk(x)的零点。可求得lk

-Demand coefficient of linear equations using the interpolation formula is relatively complex structure, construction method can use interpolation. Nodes xi (i = 0,1, ..., n) in any point xk (0 < = k < = n) n as a polynomial lk (xk), making it the point value of 1, In the remaining points xi (i = 0,1, ..., k-1, k+1, ..., n) for the 0, then polynomial interpolation Ln (x) = y0l0 (x)+ y1l1 (x)+ y2l2 (x)+ ...+ ynln (x) the type that: n points xi (i = 0,1, ..., k-1, k+1, ..., n) is lk (x) of zero. Can be obtained lk