Compress-Decompress algrithms

Development Platform:

Matlab

Douglas-Peucker.m：Code Content

							function y=f21(x)
e=0.5;
x=0:0.01:2;
y=sin(12*x.^2);
plot(x,y);
hold on;
t=zeros(1,200);
d=zeros(1,200);
for i=2:199
    plot(x(1),y(1),'*');
    hold on
    A=(y(200)-y(1))/sqrt((y(200)-y(1))^2+(x(200)-x(1))^2);
    B=(x(200)-x(1))/sqrt((y(200)-y(1))^2+(x(200)-x(1))^2);
    C=(x(200)*y(200)-x(1)*y(1))/sqrt((y(200)-y(1))^2+(x(200)-x(1))^2);
    d(i)=abs(A*x(i)+B*y(i)+C)/sqrt(A^2+B^2);
    dh=max(d(i));
    if d(i)==dh
        t=i;
    end
    if dh>e
        plot(x(t),y(t),'*');
        hold on;
        break;
    end
end
for j=2:t-1
    A=(y(t)-y(1))/sqrt((y(t)-y(1))^2+(x(t)-x(1))^2);
    B=(x(t)-x(1))/sqrt((y(t)-y(1))^2+(x(t)-x(1))^2);
    C=(x(t)*y(t)-x(1)*y(1))/sqrt((y(t)-y(1))^2+(x(t)-x(1))^2);
    d(j)=abs(A*x(j)+B*y(j)+C)/sqrt(A^2+B^2);
    dh=max(d(j));
    if d(j)==dh
        t=j;
    end
    if dh>e
        plot(x(t),y(t),'*');
        hold on;
     end
end
for k=t+1:199
    A=(y(200)-y(t+1))/sqrt((y(200)-y(t+1))^2+(x(200)-x(t+1))^2);
    B=(x(200)-x(t+1))/sqrt((y(200)-y(t+1))^2+(x(200)-x(t+1))^2);
    C=(x(200)*y(200)-x(t+1)*y(t+1))/sqrt((y(200)-y(t+1))^2+(x(200)-x(t+1))^2);
    d(k)=abs(A*x(k)+B*y(k)+C)/sqrt(A^2+B^2);
    dh=max(d(k));
    if d(k)==dh
        t=k;
    end
    if dh>e
        plot(x(t),y(t),'*');
        break;
    end
end

						