Absolute value

Returns the absolute value of a numeral or temporal, returns null for null.

Syntax: abs x; abs[x]

o)abs 1.0 -10.5 0
1 10.5 0
o)abs 0N
0N

abs is fully atomic:

o)abs (1;-2 3;-4 5 6.0)
1
2 3
4 5 6f