gusucode.com > matlab通信工程仿真源码（张德丰等编著）程序书籍 > matlab_code/matlab通信工程仿真源码（张德丰等编著）/第9章/li9_25.m

     clear all;
x=-1:0.01:1;
y=1./(1+9*x.^2); 
plot(x,y,'b'); hold on;   %原始函数曲线
xs=[-1 -0.4 -0.1 0 0.3 0.7];   %样本位置
ys=1./(1+9*xs.^2); 
plot(xs,ys,'rp');  hold on;    %样本点
xi=-1:0.07:1;     %插值位置
yi=interp1(xs,ys,xi,'linear','extrap');  %线性插值,并外插
plot(xi,yi,'m.');
yi=interp1(xs,ys,xi,'nearest');  %邻近点插值
plot(xi,yi,'-.'); 
yi=interp1(xs,ys,xi,'pchip');  %立方插值
plot(xi,yi,'+'); 
yi=interp1(xs,ys,xi,'spine');  %样条插值;
plot(xi,yi,'s');  
legend('原始函数','样本点','线性插值','邻近点插值','立方插值','样条插值');