strings (dollar.cents) into floats
Steve Holden
steve at holdenweb.com
Fri Aug 31 10:59:51 EDT 2007
Ben Finney wrote:
> Wildemar Wildenburger <lasses_weil at klapptsowieso.net> writes:
>
>> But what use is there for floats, then? When is it OK to use them?
>
> When one is willing to sacrifice decimal precision for speed of
> calculation, and doesn't need the numbers to stay precise. E.g. when
> performing millions of calculations on real-world (analogue)
> measurements.
>
Traditionally, mainframe computers used BCD arithmetic to handle
currency, and the Decimal module is probably the best way to proceed if
your Python is recent enough to include it.
That isn't to say that currencies can't be handled using floating-point.
The important thing then becomes to round after each calculation rather
than allowing the errors to build up until they become significant
enough to make a difference to the final result.
regards
Steve
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