Correct signum
function according to the Haskell report.
#60
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In Haskell,
signum x
is defined to be -1 if x is negative, 1 if it is positive, and 0 if x is 0.(In particular,
signum x * abs x ≡ x
should hold.)This is different from ArrayFire's
sign
function (which yields 1 for a negative number and 0 else), but it can be implemented in terms of that function:x
, we haveA.sign (-x) - A.sign x = 0 - 1 = -1
x=0
, we haveA.sign (-x) - A.sign x = 1 - 1 = 0
x
, we haveA.sign (-x) - A.sign x = 1 - 0 = 1