Remove integer domain example that doesn't work

[AnjoMan]

I tried this in julia 1.0.2 and it seems that the interepreter is smart enough now to interpret the expression as a float

julia> 2^-1
0.5

[Keno]

This was fixed by making exponents with integer literals special syntax:

julia> a = -1
-1

julia> 2^a
ERROR: DomainError with -1:
Cannot raise an integer x to a negative power -1.
Make x a float by adding a zero decimal (e.g., 2.0^-1 instead of 2^-1), or write 1/x^1, float(x)^-1, or (x//1)^-1
Stacktrace:
 [1] throw_domerr_powbysq(::Int64, ::Int64) at ./intfuncs.jl:176
 [2] power_by_squaring(::Int64, ::Int64) at ./intfuncs.jl:196
 [3] ^(::Int64, ::Int64) at ./intfuncs.jl:220
 [4] top-level scope at none:0

julia> 2^-1
0.5

The documentation should reflect this distinction and I just now notice that that error message should probably be updated also.

[StefanKarpinski]

Arbitrarily large integer literals are supported. Full stop.

[AnjoMan]

@Keno I think this addresses your point about the error message suggestion. It adds a suggestion for 2^-1.0, as well as calling float on the exponent (i.e. 2^(float(p))) which should cover the literal and expression cases.

[fredrikekre]

Thank you, and welcome as a contributor to Julia!