matlab插值程序

%代码首洞如下

data=[3.946       0

5.193    50

5.762   100

6.311   150

6.795   200

7.257   250

7.704   300

8.170   让早350

8.603   400

9.073   450

9.511   500

10.001   550

10.435   600

10.932   650

11.400 700

11.938 750

12.428   800

12.995   850

13.560   900

14.246  坦芹雀 950

15.063   1000]

y=data(:,1)x=data(:,2)

xx=min(x):10:max(x)

yy=interp1(x,y,xx)

plot(xx,yy,'*r',x,y,'ob')

xlabel('NtD(20ns)'),ylabel('测量值(um)'),title('***曲线')

legend('分段差值数据','千分尺数据')

结果：

使用Lagrange 插值多项式的方法：

首先把下面的代码复制到M文件中，保存成lagran

function [C,L]=lagran(X,Y)

% input - X is a vector that contains a list of abscissas

% - Y is a vector that contains a list of ordinates

% output - C is a matrix that contains the coefficients of the lagrange interpolatory polynomial

%- L is a matrix that contains the lagrange coefficients polynomial

w=length(X)

n=w-1

L=zeros(w,w)

for k=1:n+1

V=1

for j=1:n+1

if k~=j

V=conv(V,poly(X(j)))/(X(k)-X(j))

end

end

L(k,:)=V

end

C=Y*L

然后在命令窗口中输入以下内容：

x=[0 0.25 0.5 0.75 1]

y=[0 0.3104 0.6177 0.7886 1]

lagran(x,y)

ans =

3.3088 -6.38513.31640.7599 0

得到的数据就是多项式兄棚各项的系数，注意最后一个是常数项，即x^0，模悄

所以表达式为:f=3.3088*x.^4-6.3851*x.^3+3.3164*x.^2 +0.7599*x

求面积就是积分求解

>>f=@(x)3.3088*x.^4-6.3851*x.^3+3.3164*x.^2 +0.7599*x

>>quad(f,0,1)

ans =

0.5509

这些点肯定是通过这个多项旦尘渣式的！

---