
I just started learning Matlab again after not having used it in months, and got some odd results 
Trying to plot tan(x), from pi/2 to pi/2 
Code:
X = (pi/2):pi/100:(pi/2);
for i = 1:length(X)
Y(i) = tan(X(i));
end;
plot(Y);
I ended up getting something that has a negative spike at 0 and positive spike at 100. Certainly doesn't look like tan(x) to me.
I'm sure it's something simple, but it's been an hour already...
Thanks!
[edit]
Ah! Ok. It seems like the big dynamic range threw Matlab off somehow. Adding clamping works.
[/edit]

You don't need that for loop, tan() and many other functions accept/output arrays:
Y = tan(X);
Also, you need to plot against an independent variable:
plot(X,Y)
It looks sharp because pi/100 isn't a small enough step size, try .01 lower