I'm curious on how to best handle constructive answers, that don't answer the question(s) asked, but are valid and constructive answers, but to something else, or in a unrelated context.

For example: A question about implementing a user dialog in the GTK toolkit (a desktop GUI toolkit), while the answer demonstrated how to (correctly) implement a HTML/JavaScript dialog using jQuery.

That is an extreme fictional example, but it preserves the essence of what I am uncertain how to deal with.

A potentially related question, is how to constructively handle automatic citation of reference material, even without a) a specific (detailed) section reference, b) the question was asked in such a matter as to suggest a lack of background knowledge expected for comprehending the referenced material.

My pet peeve version of this is the near-automatic or robotic citation of David Goldberg's excellent and classic, What every Computer Scientist Should know about Floating-point Arithmetic article freely available from Oracle (then Sun Microsystems) and validlab.

My problem is primarily twofold, first, it (1991) pre-dates the discussion of most recent edition of the referred standard (IEEE 754-2008), and the hardware of present day systems, namely proliferation of 64-bit OS and CPUs, FPU architecture, and included availability of SIMD instruction sets/support.

But far more common as a concern is the automatic parroting of its citation, if it is not clear, or even when it is blatantly clear in the negative, that the OP has a sufficient background to comprehend Goldberg's paper, by not having the implicitly assumed background education. Namely a graduate degree in Computer Science, as per the article's title, which was a valid assumption for the article's original audience (in the original journal publication, and even subsequent online collection with Sun Microsystem's Numerical Computation Guide material).

It seems to me that many experienced and veteran members will reference the material, without fail on any scientific or floating point based question, often without a specific citation of what section details with the particular question asked.

I forgot to mention that the article is 94 pages long in PDF (US letter) format.

While I am entirely for, and encourage, leading the asker to find their own answers, I also realize that learner needs to be able to comprehend and digest the material for it to be effective.

While numerical analysis, floating point calculations, and scientific computing are complex fields with numerous (perhaps uncountably infinite) subtle traps for unsuspecting programmers, the flippant usage of citing this article seems incongruent with the ethos of Stack Overflow of being non-exclusive or simply not tolerating snobbery. Though I am confident that it is primarily an accidental or unintended behaviour.

Navel gazing: I was unable to find a combination of search terms that produces any promising "similar questions."

  • Here's another example: stackoverflow.com/a/12148136/104790 – Nikolai Ruhe Oct 23 '14 at 9:37
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    “it is not clear, or even if it is blatantly clear in the negative, that the OP has a sufficient background to comprehend [What every computer scientist]” and, in the case of this particular document, in many cases, neither is it clear that the person citing the document comprehends it. – Pascal Cuoq Oct 23 '14 at 11:19
  • If a question happens to attract a lot of answers which would be good answers to a similar question which the people who wrote the answers probably thought the original poster meant, and hasn't attracted any answers to what the OP intended, would it be better for the OP to edit the question to match intent, or to edit the question to match the answers and then ask a separate question which better clarifies what he was actually seeking? – supercat Oct 23 '14 at 16:26
  • @PascalCuoq Touché – mctylr Oct 23 '14 at 17:29
  • If it helps the discussion, I asked a question years ago that still gets answers to a similar question. In fact, the highest rated answer is to a different question. Someone linked my question and a version of the similar question ,which I thought was helpful. Someone else suggested the other question had the answer to my (four year old) question, which I did not think was helpful. stackoverflow.com/questions/840781/… – Scott Saunders Oct 23 '14 at 20:40
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    Before down-voting the answer, check that the question has not been transformed between the time when the answer was plausibly started and what you're now seeing. Sometimes (not very often, but sometimes) the answer may have been (more) relevant to a previous edition of the question, but the question may have been edited radically, leaving the original answer(s) looking silly and off-topic. Remember that the edit might not show up in the record if it was made in the first five minutes, though that's even more unlikely to be a problem (it normally takes longer than 5 minutes to transform it). – Jonathan Leffler Oct 23 '14 at 20:48
  • Remember that the answers are not just for OP, but for the other people who will find the answer later. Limiting the resources referenced because they might not be useful to one reader, even if that one is the OP, would not be good. – David Conrad Oct 25 '14 at 5:02
  • Related: meta.stackexchange.com/questions/185159/… – Sam Hanley Mar 5 '15 at 20:45

In the best case, these are XY problems where they don't address the actual question.

With the notable exception of "No, you can't do this, here's how to get where you want though" (with these, there is ideally an explanation of why you can't do it); these answers are not useful, since they don't address the actual question. Downvote, as the answers are not useful.

I would always leave a comment in these scenarios asking the OP to address the parameters of the actual question.

To your edit/sample; the answer is the same. If someone is asking about floating point rounding, pointing only to a Comp. Sci. paper probably isn't very useful. The answer should answer the question, with using the paper as a reference if applicable.

Something like (note that this answer may not be completely correct, you get the idea though):

Floating point numbers will round that far out, so you need to use a function like Math.Round when comparing them.

See David Goldberg's excellent article (insert reference/link here) for more information about this and other "gotchas" of floating-point numbers.

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    "You can't get there in a car. You need a plane, a boat, or Dumbledore's arm" are some of the most helpful answers that we have because they completely blow away common misconceptions that future readers might have very quickly once they find them. It's really nice to not waste a week chasing a dead end. That's why it's important to down-vote answers that just completely miss the question instead of saying "+1 I love jQuery and hate math too!" Good answer :) – Tim Post Oct 23 '14 at 1:06
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    @TimPost +1 for disapparation reference from HP :D – user3459110 Oct 24 '14 at 5:46
  • @vba4all the problem with Office Interop isn't that it is slow. It is that it is unreliable and prone to bugs due to internal state. – Aron Oct 27 '14 at 23:19

Good answer but not to the right question is also kind of unhelpful and deserves to be downvoted for this. SO works also because questions and answers are fitting to each other. If this is not the case anymore we will all lose valuable time searching around more than necessary.

However I would comment before downvoting, suggesting one of the following:

  • "Your post while useful does not answer the question. Please adapt it to more closely and respond to the specific problems of the question." - if I think the answer can be adapted to the question.

  • "It may be you answered the wrong question. This answer does not seem to be helpful for this question." - if I just think the answer has nothing to do with the question and is not that great.

  • "Your post answers a different question and is not really useful for this question. Please consider find a better question for your answer or pose a question suitable for your answer." - if I think the answer has not much to do with the question but sounds really intriguing.

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    Remember that you can also revert your downvote after an edit, so you can downvote immediately as extra "motivation" to fix the post. – BradleyDotNET Oct 23 '14 at 15:16

To some people, if you don't have a minimal grip on the most basic characteristics of binary floating point, you aren't 'a professional or enthusiast' qualified to play on stack overflow. You don't cite the 95 page paper so that they will read it and learn. You cite it as a shot upside the head so that they will realize that they have a serious gap in their basic craft skills that they need to fill, somehow.

Really filling in what these people are missing is too much material for a StackExchange answer. Handing them a cargo-cult recipe is not teaching them to fish.

The polite thing to do is to link to the article in a comment, "Floating point is hard; for example, see LINK. It's not possible to paint the picture in an answer here."

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