[Tutor] Need help with rewriting script to use Decimal module
Terry Carroll
carroll at tjc.com
Thu Jan 4 17:20:41 CET 2007
On Wed, 3 Jan 2007, Dick Moores wrote:
> Terry, I just noticed that farey(0.36, 10) returns (1, 3), a pretty
> big miss, IMO. The correct fraction with smallest error and maximum
> denominator of 10 is 3/8, which I'm proud to say my klunky frac.py
> (<http://www.rcblue.com/Python/fracForWeb.py>) produces.
Dick, good catch. Consider adding a comment to the Cookbook page pointing
out that the method sometimes does not produce the incorrect answer,
including for that input.
I note that the web page for the recipe says only that its produces "a
rational," not necessarily the closest rational, but the description in
the book says it's the closest:
You have a number v (of almost any type) and need to find a rational
number (in reduced form) that is as close to v as possible but with a
denominator no larger than a prescribed value. (Recipe 18.13)
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