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- Subject: Re: Possible improvements to the LNUM patch?
- From: glen@...
- Date: Mon, 14 Apr 2008 16:44:40 -0600 (MDT)
>Financial calculations are usually done in tenths of cents.
If you use doubles the input data should be checked to make sure there are
only 2 (or 3, if required) places past the decimal. Similar for using
cents.
> 23bit, completely insufficient. So let's hope we are talking about
"double" instead.
Sorry! Of course I meant double, the native Lua number type.
> If we are looking at tenth of cents, an IEEE double will take us all the
way to 2^53-1, which is 9007199254740991, namely $9,007,199,254,740.991.
That's not even a safety margin of 2 for the current gross deficit.
I stand corrected. I therefore agree, if you need to deal with REALLY
large financial transactions, you need something better than a double.
For almost all apps, A double should be fine, using one of the two
techniques I outlined.
Thanks for the corrections!
Glen.