# [Tutor] converting decimals to fractions

**alan.gauld@bt.com
**
alan.gauld@bt.com

*Wed, 10 Oct 2001 10:22:40 +0100*

Hi Blake,
Two points to make:
1) Your method will work.
2) Its not the most efficient way to use a dictionary.
Given (2), another approach which might(I haven't tested
this!) be more efficient is to extract the fractional part,
round to the required precision - looks like 6 digits then
do a binary chop search on a list of tuples. The
indexing/sequential access of the list might in this
case be better than searching the values of a dictionary.
(Wth 64 entries your *worst* case should be 6 tests...)
The tuples would of course contain the fraction string
and the equivalent number equivalent. As ever with floats
beware of rounding errors.
Just some thoughts.
Alan G.