wait a minute. I did not really look at the code, and I know nothing about it at all. The short glance I took at the trace showed me that I did not understand it at all, and I do not propose to spend more time looking at it. (That is not because I do not care about code quality and correctness, I just have other things I need to do!)
John On 27 August 2010 10:03, Dr. David Kirkby <david.kir...@onetel.net> wrote: > On 08/27/10 09:17 AM, John Cremona wrote: >> >> On 27 August 2010 07:25, Dr. David Kirkby<david.kir...@onetel.net> wrote: >>> >>> On 08/24/10 02:06 PM, kcrisman wrote: >>>> >>>> Anyway, I think (as you have correctly noted before) we have a bit of >>>> a culture clash between software engineering and mathematics. >>> >>> <SNIP> >>> >>> >>>> Just have patience with those of us who aren't from a software >>>> background - and trust that we are trying hard to internalize your >>>> lessons, but that we have more immediate needs to fill as well for our >>>> next course or paper. I think that just as Minh's messages about >>>> documentation are slowly taking hold in the whole ecosystem, so are >>>> yours about software engineering. >>>> >>>> - kcrisman >>> >>> >>> Just to make a point, my own background is not software engineering. My >>> first degree is in electrical and electronic engineering, my masters in >>> microwaves and optoelectronics and my PhD in medical physics. Apart from >>> a >>> very brief spell (about 6 months), I have never worked in the IT >>> industry. >>> >>> I first became aware of the subject of software engineering when an >>> Australian guy joined the department I worked at University College >>> London. >>> Russel's task was to develop some hardware and software for a research >>> project. He quite rightly realised that developing software "by the seat >>> of >>> your pants" as he called it was not the way to go about it. So before >>> starting to write the software, he purchased a book on the subject of >>> software engineering. >>> >>> I never gave this topic much more thought until I started working on >>> Sage. I >>> then because to realise that Sage needs to take a more professional >>> approach >>> to the development, as it seems a bit add-hock to me. >>> >>> My own view is I'd rather have something with less features, which I >>> could >>> rely on, than lots of features I don't trust. When there is little in the >>> way of project management, and a culture of not doing anything properly, >>> then attitude tends to spread like a virus. >>> >>> I'm currently running the doctests 100 times on a machine, with the same >>> build of Sage that passed all doc tests. This is an interesting failure I >>> observed: >>> >>> sage -t -long devel/sage/doc/en/constructions/linear_algebra.rst >>> ********************************************************************** >>> File >>> >>> "/export/home/drkirkby/sage-4.5.3.alpha2/devel/sage-main/doc/en/constructions/linear_algebra.rst", >>> line 202: >>> sage: A.eigenvalues() >>> Expected: >>> [3, 2, 1] >>> Got: >>> [3, 1] >>> ********************************************************************** >>> >> >> That is very worrying. The matrix A here is >> >> [1 1 0] >> [0 2 0] >> [0 0 3] >> >> over the rationals, so if eigenvalues are being missed it is in >> finding the roots of a rational cubic whose roots are 1,2,3. I tried >> tracing through the call to A.eigenvalues() but that is hard to do >> since it spends ages doing things whose necessity is hard to >> understand (for example, there are calls to cputime()!). >> >> John > > Thank you for looking at this John. > > I think you have just proved one of the points I tried to make John. > > * I spend some time testing multiple times and observe that failure, once in > 47 runs of the doctests. > > * You look at the code and find it's dubious. Calling cputime() when > computing eignevectors does seem a bit odd. Even I know that. But this is > getting past the review process. > > If you want, I can create a trac ticket for this, or perhaps its better if > you do it, since you know more about the code. The test procedure was > > * Sun Ultra 27 > * 3.33 GHz quad core Xeon (hyperhtreaded) > * OpenSolaris 06/2009. > * 12 GB RAM > * Totally unmodified sage-4.5.3.alpha2 > * Running 'make ptestlong' in a loop which executes that 100 times. > * The failure was obsevved once in 47 runs to date. > > There are other suspicious failures I've observed, but that one stuck me as > particularly worrying as the result seemed to look believable. When you get > a traceback, it's obvious something has gone wrong. But in this case it's > less obvious. > > Dave > > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to > sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org > -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
