Why do Rationals promote to Floats

[Tamas_Papp]

@thelonious

I’m wondering, is there an explanation or discussion about this that I can read? If I wanted to reverse this behavior (convert the Float to a Rational in this case), is that something I can override?

I think the reason is that

1. calculations with eg Rational{Int64} would quickly overflow for the denominator,

2. the results of transcendental functions (exp) cannot be a rational number in general.

So it is safest to promote to Float64. Of course, the trade-off is floating point inaccuracy.

Generally, I would just not promote but leave it to the operation. For a more specific workaround, please provide more context.

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