MATLAB程序设计与应用刘卫国（第三版）课后实验答案——7

一

x=linspace(0,2*pi,101);y=(0.5+3.*sin(x)./(1+x.^2)).*cos(x);plot(x,y)

x=-5:0.01:5;y=((x+sqrt(pi))/exp(2)).*(x<=0)+(0.5.*log(x+sqrt(1+x.^2))).*(x>0);plot(x,y)

theta=0:pi/100:2*pi;a=input('输入a=');b=input('输入b=');c=input('输入c=');rho=a.*sin(b+c.*theta);polar(theta,rho,'m')

二

x=-pi:pi/100:pi;y1=x.^2;y2=cos(2*x);y3=y1.*y2;plot(x,y1,'b-',x,y2,'r',x,y3,'k--');

x=-pi:pi/100:pi;y1=x.^2;y2=cos(2*x);y3=y1.*y2;subplot(1,3,1);plot(x,y1,'b-');title('y1=x^2');subplot(1,3,2);plot(x,y2,'r:');title('y2=cos(2x)');subplot(1,3,3);plot(x,y3,'k--');title('y3=y1*y2');

x=-pi:pi/100:pi;y1=x.^2;y2=cos(2*x);y3=y1.*y2;subplot(2,2,1);plot(x,y1,'b-',x,y2,'r:',x,y3,'k--');subplot(2,2,2);bar(x,y1,'b');%此处条形图改为stairs；杆图为stem；填充图为filltitle('y1=x^2');subplot(2,2,3);bar(x,y2,'r');subplot(2,2,4);bar(x,y3,'k');title('y3=y1*y2');

三

t=0:pi/100:2*pi;x=(2+cos(t./2)).*cos(t);y=(2+cos(t./2)).*sin(t);z=sin(t./2);plot3(x,y,z,'p');title('3D picture');xlabel('X'),ylabel('Y'),zlabel('Z');grid;

四

x=linspace(-5,5,21);y=linspace(0,10,31);[x,y]=meshgrid(x,y);z=cos(x).*cos(y).*exp(-sqrt(x.^2+y.^2)/4);subplot(2,1,1);surf(x,y,z);title('曲面图');subplot(2,1,2);surfc(x,y,z);title('等高线图')

五

s=0:pi/100:pi/2;t=0:pi/100:3*pi/2;[s,t]=meshgrid(s,t);x=cos(s).*cos(t);y=cos(s).*sin(t);z=sin(s);subplot(2,2,1);mesh(x,y,z);title('未着色');subplot(2,2,2);surf(x,y,z);title('缺省');subplot(2,2,3);surf(x,y,z);shading flat;title('shading flat');subplot(2,2,4);surf(x,y,z);shading interp;title('shading interp');