User-defined function syntax:
<function-name> ( <dummy-var> ) = <expression>
Where <expression> is defined in terms of <dummy-var>.
User-defined variable syntax:
<variable-name> = <constant-expression>
Examples:
w = 2
q = floor(tan(pi/2 - 0.1))
f(x) = sin(w*x)
sinc(x) = sin(pi*x)/(pi*x)
delta(t) = (t == 0)
ramp(t) = (t > 0) ? t : 0
The variable pi is already defined for you.
See show functions and show variables.