摘要
以多项式(1+x)Vn(x)=(1+x)cos[(2cons(+θ1/)2()θ/2)](x=cosθ,0≤θ≤π)的零点作为插值节点,采用线性组合的方法构造了一个组合型的多项式算子Wn,r(f,x),如果f(x)∈C[j-1,1](0≤j≤r,r为任意奇自然数),则Wn,r(f,x)对f(x)的逼近程度达到最佳,即Wn,r(f,x)-f(x)=O(n+11)jω(f(j),Δn(x))+(2n+11)j+1,其中Δn(x)=1-x2,O与n,f,f(j)无关.
Here we work out a combinational operator Wn,r (f,x) with zeros of the polynomial (1+x)Vn(x)=(1+x)cos[(2n+1)(θ/2)]/cos(θ/2)(x=cosθ,0≤θ≤π) through the method of combination average. Convergence order of the operator Wn,r(f,x) is the best if f(x) ∈ C[-1,1]^j (0≤j≤r, where r is an arbitrary odd natural number) , that is |Wn,r(f,x)-f(x)|=O[1/(n+1)^jω(f^(j),△n(x))+1/(2n+1)^j+1] where △n(x)=√1-x^2/n+1 , O is independent of n, f, f^(j).
出处
《吉林大学学报(理学版)》
CAS
CSCD
北大核心
2007年第1期29-34,共6页
Journal of Jilin University:Science Edition
关键词
LAGRANGE插值多项式
点态逼近阶
线性组合
算子
Lagrange interpolation polynomial
pointwise approximation order
linear combination
operator