How to make nsimplify give approximate fraction

[Paul Royik]

nsimplify((Integer(149)/25).evalf()) outputs 149.25, as expected

nsimplify((Integer(149)/35).evalf()) outputs 149/35, which is not expected as it is repeating decimal.

How to make it perform approximation to given precision: 4257142857142857/10**15 ?

[Aaron Meurer]

I'm not sure if you can get that with nsimplify(). I tried playing
with the tolerance and rational_conversion arguments, but it either
tries to be smart and reconstruct the original fraction, or it gives
the exact base-2 fraction represented by the float
(4793116746272885/1125899906842624).

If I understand correctly, you want to take this decimal

>>> (Integer(149)/35).evalf()
4.25714285714286

and re-interpret it as a base-10 rational. You can convert it to a
string and use Rational(), like

>>> Rational(str((Integer(149)/35).evalf()))
212857142857143/50000000000000

To get the version you mentioned, you should use

>>> (Integer(149)/35).evalf(16)
4.257142857142857
>>> Rational(str((Integer(149)/35).evalf(16)))
4257142857142857/1000000000000000

Aaron Meurer

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[Paul Royik]

Thank you. It works.

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