Ceiling is defined in terms of Floor as ⌈Y←→-⌊-Y
Y must be numeric.
If an element of Y is real, the corresponding element of R is the least integer greater than or equal to the value of Y.
If an element of Y is complex, the corresponding element of R depends on the relationship between the real and imaginary parts of the numbers in Y.
⌈¯2.3 0.1 100 3.3 ¯2 1 100 4 ⌈1.2j2.5 1.2j¯2.5 1J3 1J¯2
For further explanation, see Floor.
⎕CT is an implied argument of Ceiling.