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Basic routines for decimal arithmetic in Julia. Supports addition, subtraction, negation, multiplication, division, and equality operations; exponentiation coming as soon as I find the time to write it. This is a pure Julia implementation, so if you are concerned about pure speed, calling `libmpdec` functions directly is likely to be faster. Tested in Julia v. 0.3.0-prerelease+4028.
Update: I have discovered recently that the built-in `BigFloat` already fills this niche in Julia. I suggest using this instead of `Decimal`, as it has a more complete feature set, and is probably faster, too :)
### Background
Why is this needed? Because floating point arithmetic does things like this:
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In the README you suggest using BigFloat instead of Decimal. BigFloat is not a good replacement for Decimal. Although it uses more bits to store the floats than Float64, it is still a binary float format that doesn't provide an exact representation for all floats.
One example:
julia> x = trunc(BigFloat("2.10") * 100) / 100
2.090000000000000000000000000000000000000000000000000000000000000000000000000015e+00 with 256 bits of precision
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In the README you suggest using BigFloat instead of Decimal. BigFloat is not a good replacement for Decimal. Although it uses more bits to store the floats than Float64, it is still a binary float format that doesn't provide an exact representation for all floats.
One example:
julia> x = trunc(BigFloat("2.10") * 100) / 100
2.090000000000000000000000000000000000000000000000000000000000000000000000000015e+00 with 256 bits of precision
julia> @printf("%.2f\n", x) # lost a penny
2.09
A Decimal package is an important compliment to BigFloat.
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Interesting, I guess I misunderstood the purpose of BigFloat. I'll have to come back and finish Decimal when I've got a bit of time, then!