Returns the absolute value of a.
If a is Long/MIN_VALUE => Long/MIN_VALUE
If a is a double and zero => +0.0
If a is a double and ##Inf or ##-Inf => ##Inf
If a is a double and ##NaN => ##NaN
;; As indicated in its documentation, abs can return a negative value!(absLong/MIN_VALUE);;=> -9223372036854775808;; This is, because -Long/MIN_VALUE > Long/MAX_VALUE:;; (* -1 Long/MIN_VALUE);;=> Execution error (ArithmeticException) at java.lang.Math/multiplyExact;;=> (Math.java:1032).;;=> long overflow