#6870: [with second patch, needs work] Bug in binomial
------------------------------+---------------------------------------------
Reporter: hgranath | Owner: somebody
Type: defect | Status: new
Priority: minor | Milestone: sage-4.1.2
Component: basic arithmetic | Keywords: binomial
Reviewer: | Author:
Merged: |
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Comment(by kcrisman):
Maybe this?
{{{
sage: var('n')
n
sage: a = n+1
sage: from sage.symbolic.expression import Expression
sage: isinstance(a,Expression)
True
sage: def g():
....: isinstance(a,Expression)
....:
sage: timeit('g()')
625 loops, best of 3: 573 ns per loop
sage: a=SR(10**7)
sage: timeit('g()')
625 loops, best of 3: 595 ns per loop
sage: timeit('f()')
625 loops, best of 3: 1.59 µs per loop
}}}
You can still use try: ZZ(x), it just makes sense to check type first,
since it adds only nanoseconds, and then if someone is silly enough to use
SR(10**7) instead of 10**7, they'll have to pay the microsecond penalty.
I jest a little, but I think you should try something like this to see if
it would work. If not, the first patch is probably better than allowing
rational things to get through. You could also add a check for rationals
instead:
{{{
sage: from sage.rings.rational import Rational
sage: def g():
....: isinstance(a,Rational)
....:
sage: timeit('g()')
625 loops, best of 3: 1.23 µs per loop
sage: a = 10**7-1/1
sage: type(a)
<type 'sage.rings.rational.Rational'>
sage: timeit('g()')
625 loops, best of 3: 570 ns per loop
}}}
So even if a isn't rational, you lose very little time by checking that
before you coerce.
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/6870#comment:5>
Sage <http://sagemath.org/>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
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