一道MATLAB编程题！！新手求高手解决！！！

x='sin'
y=[1 1 0]
myfun(x,y)

当前文件夹新建一个文件，文件名myfun.m内容如下：
function f=fun(x,y)
m=-1:0.01:1;
switch x
case 'sin'
plot(m,y(1)*sin(2*pi*y(2)*m+y(3)*pi/180),'b-.')
grid on
text(0.6,0.9,'yuyuefly','FontSize',13)
text(0.6,0.7,'000000','FontSize',13)
case 'cos'
plot(m,y(1)*cos(2*pi*y(2)*m+y(3)*pi/180),'r:')
grid on
text(0.6,0.9,'yuyuefly','FontSize',13)
text(0.6,0.7,'000000','FontSize',13)
case 'rand'
plot(m,rand(1,length(m)),'k-')
grid on
text(0.6,0.9,'yuyuefly','FontSize',13)
text(0.6,0.7,'000000','FontSize',13)
case 'sin-'
plot(m,y(1)*exp(-m).*sin(2*pi*y(2)*m+y(3)*pi/180),'g--')
grid on
text(0.6,0.9,'yuyuefly','FontSize',13)
text(0.6,0.7,'000000','FontSize',13)
otherwise
disp('Unknown method.')
end