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bus or segmentation fault calling integrate

asked 2019-10-26 11:05:50 -0500

Nasser gravatar image

updated 2019-10-26 11:10:48 -0500

Why does sagemath crash on this integrate? Running this inside Linux Manjaro in a VBox.

>sage
┌────────────────────────────────────────────────────────────────────┐
│ SageMath version 8.9, Release Date: 2019-09-29                     │
│ Using Python 2.7.16. Type "help()" for help.                       │
└────────────────────────────────────────────────────────────────────┘
sage: var('a b c d e f m n p x ')
(a, b, c, d, e, f, m, n, p, x)
sage: integrate((c*cos(b*x+a)^m)^(3/2),x)

And after about 20-30 seconds sagemath crashes

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


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

Strange thing is it crashes when exponent is 3/2 but not when exponent is 5/2

I remember seeing such crashes in sagemath before, but I thought this was fixed.

Is this a known bug or something new?

Thanks --Nasser

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answered 2019-10-26 23:06:42 -0500

nbruin gravatar image

Looks a lot like the reports on https://trac.sagemath.org/ticket/25636 by someone who shares your name.

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thanks for finding this ticket. But are you sure this is the same bug and not new one? I tried the bug shown in the ticket. And that one do not core dump any more in sagemath 8.9

>sage
│ SageMath version 8.9, Release Date: 2019-09-29                     │
│ Using Python 2.7.16. Type "help()" for help.                       │
sage:  var('x m a b')
(x, m, a, b)
sage: integrate(x^m/sqrt(a + b*x^(2 - m)), x)
integrate(x^m/sqrt(b*x^(-m + 2) + a), x)
sage:

Also tried integrate((c*cos(b*x + a)^m)^(5/2),x) shown in the ticket. It also did not crash. Notice that the ticket is 1.5 years old. So I expected that the bug there was fixed? I do not know. But if you sure this post is duplicate of the ticket you linked to, that is all fine with ...(more)

Nasser gravatar imageNasser ( 2019-10-27 02:08:59 -0500 )edit

The error message shown here indicates it's maxima that blows up, and indeed, if you include the right initialization code in maxima, it crashes on this example. So it's a bug in maxima, as the other bugs are, The place to report them to get them worked on is maxima. The ticket referenced above is a dumping ground of (probably) maxima-related integration faults anyway. There's nog guarantee the examples there ae actually listed. So if you want to keep track of this example on trac too, then that ticket is a good one to put the example. The only way for that ticket to make progress is if someone takes the effort of reporting the cases listed there to maxima, in a way that the behaviour shows in maxima directly.

nbruin gravatar imagenbruin ( 2019-10-27 11:17:31 -0500 )edit

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Asked: 2019-10-26 11:05:50 -0500

Seen: 87 times

Last updated: Oct 26 '19