[Groff] couple of questions regarding pic

[Wolfgang Huber]

Hi!

I got a couple of questions:

1) is it possible to rotate an object?
for example "box rotated 45 degrees"?
(i know i could input an eps-file but I would prefer a pic-solution)
2)plotting of functions
there are examples both in the Kernighan manual and the manual by Eric S
Raymond but they are with centered types. 
I made my own version but it just generates nonsense:
.PS
pi = atan2(0,1)
for i = 0 to 2 * pi by 0.1 do {
"-" at i/2 , 0
}
move left 2 * pi
for i = 0 to 2 * pi by 0.1 do {
line to i/2 , sin(i)/2
}
.PE

What is wrong?

TIA

Wolfgang