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Decimal to fraction?

asked 2013-09-15 12:29:57 +0200

bxdin gravatar image

I did .1/8, and the output was 0.0125000000. Is there a way to get it to display as 1/80.

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answered 2013-09-15 13:20:29 +0200

tmonteil gravatar image

updated 2013-09-15 13:33:41 +0200

There are at least three ways to recover a rational from one of its numerical approximations:

sage: a = .1/8
sage: a.simplest_rational()
sage: a.nearby_rational(0.0001)
sage: a.exact_rational()

You can have a look to their respective documentations to see the differences. And you should understand that the floating point number a is not equal to 1/80 but to 3602879701896397/288230376151711744 !

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answered 2013-09-15 13:20:25 +0200

ppurka gravatar image
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it is fun as also the answers are duplicate ;-)

vdelecroix gravatar imagevdelecroix ( 2013-09-16 09:12:34 +0200 )edit

answered 2013-09-15 16:24:34 +0200

dazedANDconfused gravatar image

updated 2013-09-15 18:51:13 +0200

I've posted an alternate answer to the question at the link above. The basic answer: I ran across another way that's posted here where the author, John D Cook mentions the nsimplify command in SymPy (which you can can access in Sage). Here's nsimplify in action with your example image description

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nsimplify is much more subtle and does not always return a rational as with nsimplify(3.2352)

vdelecroix gravatar imagevdelecroix ( 2013-09-16 09:11:38 +0200 )edit

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Asked: 2013-09-15 12:29:57 +0200

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Last updated: Sep 15 '13