一个能画出好看图片的小程序呀 补动图： 
树枝长度，树枝角度都可以调的
完整代码：
function binary2
hold on,axis equal
axis(0.5+[0,40,0,40])
set(gca,'xtick',[],'ytick',[],'xcolor','w','ycolor','w')
set(gca,'color','k')
length_trunk=6;
width_trunk=3;
k1=0.8;k2=0.8;
number_branch=10;
alp=pi/10;
length_branch=k1*length_trunk;
width_branch=k2*width_trunk;
trunk=[20,0;20,length_trunk];
plot(trunk(:,1),trunk(:,2),'w','Linewidth',width_trunk)
begins=[trunk(2,:),pi/2];
grow=begins;
for i=1:number_branch
ag=grow(:,3);
l=length(ag);
parta=[length_branch*cos(ag+ones(l,1)*alp),length_branch*sin(ag+ones(l,1)*alp),ones(l,1)*alp];
partb=[length_branch*cos(ag-ones(l,1)*alp),length_branch*sin(ag-ones(l,1)*alp),-ones(l,1)*alp];
parta=parta+grow;
partb=partb+grow;
congress=[parta;partb];
grow=[grow;grow];
pla=[grow(:,1),congress(:,1)];
plb=[grow(:,2),congress(:,2)];
pla=pla';plb=plb';
plot(pla,plb,'w','Linewidth',width_branch)
grow=congress;
length_branch=k1*length_branch;
width_branch=k2*width_branch;
pause(0.05)
end
end
