exp4_1.m

使用matlab软件编制的计算程序

% exp4_1.m --- 一维插值命令的学习

% yi = interp1(x,y,xi,'method') 
% x,y 是插值节点,xi 是插值的自变量,yi 是插值函数值
% method 含义如下
%           linear  ---  线性插值
%           cubic   ---  三次多项式插值
%           spline  ---  三次样条插值(相当于 spline(x,y,xi) 后面用专门介绍)
%           nearst  ---  最近邻插值


x = linspace(0,2*pi,7);
y = sin(x);
xi = linspace(0,2*pi,101);

yi = interp1(x,y,xi,'linear');
subplot(2,2,1)
plot(x,y,'o',xi,sin(xi),xi,yi)
axis([0 2*pi -1.2 1.2])
title('linear 插值')

yi = interp1(x,y,xi,'cubic');
subplot(2,2,2)
plot(x,y,'o',xi,sin(xi),xi,yi)
axis([0 2*pi -1.2 1.2])
title('cubic 插值')

yi = interp1(x,y,xi,'spline');
subplot(2,2,3)
plot(x,y,'o',xi,sin(xi),xi,yi)
axis([0 2*pi -1.2 1.2])
title('spline 插值')

yi = interp1(x,y,xi,'nearst');
subplot(2,2,4)
plot(x,y,'o',xi,sin(xi),xi,yi)
axis([0 2*pi -1.2 1.2])
title('nearst 插值')