clc
clear
%(a)
plot(-2*pi:0.1:2*pi,sin(-2*pi:0.1:2*pi)./(-2*pi:0.1:2*pi),'r-.')
%(b)
figure(2)
x=-1:0.05:1;
[x,y]=meshgrid(x,x);
z=x.^2+2*y.^2;
subplot(2,1,1)
mesh(x,y,z)
subplot(2,1,2)
surf(x,y,z)
%c
figure(3)
t1=(0:11)/11*pi;
y1=sin(t1).*sin(9*t1);
t2=(0:100)/100*pi;
y2=sin(t2).*sin(9*t2);
subplot(2,2,1),plot(t1,y1,'r.'),axis([0 pi -1 1]),title('åå¾ï¼1ï¼'),gtext('ä¸å¤ªå®æ´')
subplot(2,2,2),plot(t2,y2,'r.'),axis([0 pi -1 1]),title('åå¾ï¼2ï¼'),gtext('å®æ´ç')
subplot(2,2,3),plot(t1,y1,t1,y1,'r.'),axis([0 pi -1 1]),title('åå¾ï¼3ï¼'),gtext('ççè¿ç»')
subplot(2,2,4),plot(t2,y2),axis([0 pi -1 1]),title('åå¾ï¼4ï¼'),gtext('æ£ç¡®çè¿ç»')