用C#实现的等距Lagrange插值代码

class Program

{

//private double[] f = {1.1052,1.2214,1.3499,1.4918,1.6487};//实验数据一

private double[] f = { -0.693147, -0.510826, -0.356675 };//实验数据二

static void Main(string[] args)

{

double result;

Program s=new Program();

// result = s.GetValueLagrange(0.285,0.1,5,0.1);

result = s.GetValueLagrange(0.54,0.1,3,0.5);

Console.WriteLine("求e^0.285插值结果是： "+result);

Console.ReadLine();

}

///一元全区间等距插值

///@param n -- 节点个数

///@param x -- 待求点的函数值

///@param h -- 节点搜索步长

///@param y[i] -- 一维数组，存放插值节点的值

///@param x0 -- 为插值初节点

///@param retturn double ,还回所求函数的近似值

public double GetValueLagrange(double x, double h,int n,double x0)

{

double p=0.0;

double[] y=new double
;

for(int i=0;i<n;i++)

{

y[i]=x0+i*h;

}

for (int i = 0; i <n; i++)

{

double m=1.0;

for(int j=0;j<n;j++)

{

if (i == j && i < n - 1)

{

j++;

m = m * ((x - y[j]) / (y[i] - y[j]));

}

else

if (i == j && i == n - 1)

{ continue; }

else

{

m = m * ((x - y[j]) / (y[i] - y[j]));

}

}

p += f[i] * m;

}

return p;

}

}