ex341.m

matlab的教程

for a=1:4;
q=-pi:.1:pi;
x=a*sin(q);
y=sqrt(25-a^2)*cos(q);
plot(x,y) 
title('绘制a=1--3的椭圆图')
text(a-1,sqrt(25-a^2)-2,['a=',num2str(a)])
hold on
end