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楼主 |
发表于 2008-12-2 17:20
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这是用正弦插值的一个例子,程序还可以改进,把精度提得更高,希望这个程序是抛砖引玉,给大家提供更多的帮助和想法,完善算法。呵呵
clc
clear
close all
for i=1:80
x(i) = sin(pi*i*0.08);
v(i) = pi*i*0.08;
end
hold on
plot(x)
Len=length(x);
[indmin,indmax,indzer] = extr(x);
indser = [indmin,indmax];% 合并极值
indser = sort(indser); % 排序(从小到大)
% 把端点作为极值处理
if indser(1) > 1
indser = [1,indser];
end
if indser(end) < Len
indser = [indser,Len];
end
a=x(indser);
b=v(indser);
plot(indser,a,'r')
x1 = x;
y=a;
x=indser;
len = length(x);
k = 1;
% 对左边端点的处理
m = x(2)-x(1);
ya(1) = asin(y(1));
ya(2) = asin(y(2));
h = (ya(2)-ya(1))/m;
delta = ya(1);
for i = 0:m
z(k) = sin(delta);
delta = delta + h;
k = k + 1;
end
k = k - 1;
% 对中间的点处理
for i = 3:len-1
m =x(i)-x(i-1);
h = (y(i-1)-y(i))/2;
delta = 4/(m);
for i = 0:delta:4
z(k) = h*sin(pi/4*i+pi/2);
k = k+1;
end
k = k - 1;
end
% 对右边端点的处理
m = x(end)-x(end-1);
ya(1) = asin(y(end-1));
ya(2) = asin(y(end));
h = (ya(2)-ya(1))/m;
delta = ya(1);
for i = 0:m
z(k) = sin(delta);
delta = delta + h;
k = k + 1;
end
% -----------------
plot(z,'g')
hold off |
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