On Mon, Nov 23, 2015 at 12:20 PM, Dima Pasechnik <dimp...@gmail.com> wrote:
>
>
> On Monday, 23 November 2015 00:43:02 UTC, William wrote:
>>
>> This definitely looks like a bug. In the meantime, a workaround is to
>> use sympy:
>>
>> sage: var('m a0')
>> (m, a0)
>> sage: x=2/5*((3/4)^m - 1)*(a0 - 1000000) + 1/5*(3*(3/4)^m + 2)*a0;x
>> 2/5*((3/4)^m - 1)*(a0 - 1000000) + 1/5*(3*(3/4)^m + 2)*a0
>> sage: limit(x, m=oo)
>> [BAD]
>> sage: limit(x, m=oo, algorithm='sympy')
>> 4000000
>>
>> I wonder -- to what extent should we be using maxima by default still
>> for limits, instead of sympy...? At some point, presumably sympy will
>> be uniformly better than maxima?
>
>
> the bug is not really in maxima, it's in Sage's interface to maxima:
>
> (%i7) limit(2/5*((3/4)^m - 1)*(a0 - 1000000) + 1/5*(3*(3/4)^m +
> 2)*a0,m,inf);
> (%o7) 400000
Note that William's result has one more zero in the answer... Which
one is correct?
Ondrej
>
> (this is with 'sage --maxima')
> probably extra maxima packages loaded along with maxima cause this OOM in
> Sage.
>
>
>>
>>
>> Public worksheet:
>>
>>
>> https://cloud.sagemath.com/projects/4a5f0542-5873-4eed-a85c-a18c706e8bcd/files/support/2015-11-22-163829-limit.sagews
>>
>> On Sun, Nov 22, 2015 at 2:00 PM, David Joyner <wdjo...@gmail.com> wrote:
>> > Forwarded to the correct list
>> >
>> > ---------- Forwarded message ----------
>> > From: G. M.-S. <list...@gmail.com>
>> > Date: Sun, Nov 22, 2015 at 4:34 PM
>> > Subject: [sage-release] Bug in limit?
>> > To: sage-r...@googlegroups.com
>> >
>> >
>> >
>> > Hello.
>> >
>> > This is my first post, please be indulgent.
>> >
>> > Is the following a bug?
>> >
>> > Thanks in advance.
>> >
>> > Guillermo Moreno-Socías
>> >
>> > ┌────────────────────────────────────────────────────────────────────┐
>> > │ SageMath Version 6.9, Release Date: 2015-10-10 │
>> > │ Type "notebook()" for the browser-based notebook interface. │
>> > │ Type "help()" for help. │
>> > └────────────────────────────────────────────────────────────────────┘
>> > sage: var('m a0')
>> > (m, a0)
>> > sage: x=2/5*((3/4)^m - 1)*(a0 - 1000000) + 1/5*(3*(3/4)^m + 2)*a0;x
>> > 2/5*((3/4)^m - 1)*(a0 - 1000000) + 1/5*(3*(3/4)^m + 2)*a0
>> > sage: limit(x,m=oo)
>> >
>> > ;;;
>> > ;;; Detected access to protected memory, also kwown as 'bus or
>> > segmentation fault'.
>> > ;;; Jumping to the outermost toplevel prompt
>> > ;;;
>> >
>> > (Note that if x is expanded then the limit is correctly calculated.)
>> >
>> > --
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>>
>>
>> --
>> William (http://wstein.org)
>
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