fix sign function for NaN

base/number.jl

@@ -77,7 +77,7 @@ signbit(x::Real) = x < 0
 Return zero if `x==0` and ``x/|x|`` otherwise (i.e., ±1 for real `x`).
 """
 sign(x::Number) = x == 0 ? x/abs(oneunit(x)) : x/abs(x)
-sign(x::Real) = ifelse(x < 0, oftype(one(x),-1), ifelse(x > 0, one(x), oftype(one(x),0)))
+sign(x::Real) = ifelse(x < 0, oftype(one(x),-1), ifelse(x > 0, one(x), typeof(one(x))(x)))
 sign(x::Unsigned) = ifelse(x > 0, one(x), oftype(one(x),0))
 abs(x::Real) = ifelse(signbit(x), -x, x)