%#########求伪零点域pseudozero set,并实现其可视化#############clear,clce=0.1%e=0.485868; % tolerance errora=[0.5 1 1]; n=length(a); %.........radius of the square..........p=0;for i=1:n-1 p=p+abs(a(i));endp=p+n*e;r=max([1;p]) ; %%step length............................b=max(abs(a));b=b^n;%表示b的n次方h=sqrt(8/(n^(n+2)))/(1+b) ; %%%...........meshgrid.......x=-r:h:r;y=x;[X,Y]=meshgrid(x,y);clear i;Z=X+i*Y;%horner schemeg=zeros(size(Z));for u=1:length(x) for v=1:length(y) clear p; p=a(n); q=abs(a(n)); for k=(n-1):-1:1 p=p*Z(u,v)+a(k); q=q*abs(Z(u,v))+abs(a(k)); end g(u,v)=abs(p)/q; endend% plot the contour lineclf %清楚曾经的figure[C1,h1]=contour(X,Y,g,[e,e],'k');%clabel(C1,h1);hold on%e=0.01;%[C2,h2]=contour(X,Y,g,[e,e],'r');%clabel(C2,h2);%plot(0.8,0,'k.','MarkerSize',10);%set(gca,'Xtick',[0.8],'Ytick',[0]);%plot(x,0);plot(0,y,':');hold off谁帮我详细解释一下这个程序，特别是meshgrid和contour(X,Y,g,[e,e],'r');怎么用和做了什么
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