Detected access to protected memory, also kwown as 'bus or segmentation fault'.

[Peleg Michaeli]

The following attempt:

sage: var('c,n')
sage: (1/(c*n^6))^log(n,2/3).limit(n=infinity)

Is ok (raises ValueError), but the following attempt:

sage: var('c,n')
sage: f = (1/(c*n^6))^log(n,2/3)
sage: f.limit(n=infinity)

hangs a little while, the prints a lot of times

;;;
;;; Detected access to protected memory, also kwown as 'bus or segmentation fault'.
;;; Jumping to the outermost toplevel prompt
;;;

and ends with a segmentation fault (core dumped).

This is on SageMath version 7.5.beta5, Release Date: 2016-12-01, built on my Ubuntu.

Should I open a ticket?


Thanks,
Peleg.

----

System info:

* Ubuntu 14.04.5 LTS (trusty)
* Architecture: 64 bit
* Kernel version: 4.4.0-57-generic
* Dell E7440
* Bios version: A14

----

Build info:

* gcc (Ubuntu 4.9.4-2ubuntu1~14.04.1) 4.9.4
* GNU Make 3.81
* m4 (GNU M4) 1.4.17
* perl v5.18.2
* GNU ar (GNU Binutils for Ubuntu) 2.24
* GNU ranlib (GNU Binutils for Ubuntu) 2.24
* tar (GNU tar) 1.27.1
* Python 2.7.6

----

Additional software:

* dvipng (dvipng (TeX Live)) 1.15
* pdfTeX 3.14159265-2.6-1.40.16 (TeX Live 2015)

[Jeremias Epperlein]

The same happens for me on Sage 7.4 on Fedora, so definitely a bug.

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[Dima Pasechnik]

IIRC I have seen this while working on https://trac.sagemath.org/ticket/18920

(and it's reported upstream - this is a Maxima or Maxima/ECL bug)

see also https://trac.sagemath.org/wiki/symbolics

[Nils Bruin]

This indeed seems to be a problem in maxima itself. With

domain : complex;
limit( (1/(c*n^6))^(log(n)/log(2/3)), n, inf);

in maxima, the same problem arises. Without "domain : complex" there is no problem, so it's an unfortunate interaction somewhere.

[Peleg Michaeli]

So all of this means that there's no need to report it on sage trac, but rather simply wait for maxima's fix?