by

y - vertical coordinate (0..1)
x - horisontal coordinate
t - day time in seconds
pi - 3.1415926...
sin, cos, tan - trigonometry
atan2 - arctangent of A/B
log - log base e
exp - e rised to the power
sqrt - square root
floor - round on downward
ceil - round on upward
abs - absolute value
negate - negate value
dup - dublicate value
over - A,B -> A,B,A
2dup - dublicate a pair
drop - delete from stack
swap - A,B -> B,A
-rot - A,B,C -> C,A,B
rot - A,B,C -> B,C,A
= - 1 if A is equal to B, 0 else
<> - 1 if not equal, 0 else
> - 1 if B greater than A
< - 1 if B<A, 0 else
>= - 1 if B>=A, 0 else
<= - 1 if B<=A, 0 else
and - boolean A&&B
or - boolean A||B
not - boolean !A
min - minimal value of A, B
max - maximum of A, B
+ - A,B -> A+B
- - A,B -> A-B
* - A,B -> A*B
/ - A,B -> A/B
mod - A modulo B
pow - rise A to B power
** - the same as pow
z+ - complex sum of 2 pairs
z* - complex multiply
push - move to return stack
>r - same as push
pop - restore from ret-stack
r> - same as pop
( ) - comments