#4612: [with patch, needs work] is_perfect_power for rationals
------------------------------+---------------------------------------------
Reporter: robertwb | Owner: somebody
Type: defect | Status: new
Priority: major | Milestone: sage-3.2.1
Component: basic arithmetic | Resolution:
Keywords: |
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Changes (by craigcitro):
* summary: [with patch, with positive review, needs review of second
patch] is_perfect_power for rationals => [with
patch, needs work] is_perfect_power for
rationals
Comment:
Actually, I retract my review above. This patch is completely wrong! In
particular, look at this:
{{{
sage: (4/27).is_perfect_power()
True
}}}
That's absolutely not a perfect power! This code is too naive. If both the
numerator and denominator are perfect powers, we need to see what powers
they are, and make sure that one of the powers divides the other. Here's a
battery of tests that needs to pass:
{{{
sage: (2/27).is_perfect_power()
False
sage: (4/27).is_perfect_power()
False
sage: (-1/25).is_perfect_power()
False
sage: (-1/27).is_perfect_power()
True
}}}
One might want even more doctests ...
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/4612#comment:2>
Sage <http://sagemath.org/>
Sage - Open Source Mathematical Software: Building the Car Instead of
Reinventing the Wheel
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