Some of the links I posted to stack overflow; the top-voted answer there (as of this writing) was wildly incorrect, claiming it to be a mistake. It is not. Any

Some of the links I posted to stack overflow; the top-voted answer there (as of this writing) was wildly incorrect, claiming it to be a mistake. It is not. Any invalid calculation produces NaN as opposed to raising an exception/signal because that would be non-portable (especially in the early 80s). The goal was that a correct algorithm on one platform or in one language would translate and be correct somewhere else. Further, some algorithms depend on being able to probe a function to find its bounds, requiring them to be able to locate the out of bounds condition without halting execution; doing that in a safe, portable way is actually quite hard unless you do it in software as part of the spec, hence NaN. If NaN==NaN, then (NaN/NaN)==1, etc etc and you still end up in a world of nonsense as far as naive algebra is concerned. This is just some of my fellow programmers whining and crying about having to think about floating point, the same sort of complaining I hear about Unicode (and full of just as much self-sure awful advice that produces wildly incorrect results for everything except the complainer's specific use case). http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.ht... http://www.eecs.berkeley.edu/~wkahan/ieee754status/754story.html http://www.eecs.berkeley.edu/~wkahan/ieee754status/754story.... http://cnx.org/content/m32770/latest/ http://cnx.org/content/m32770/latest/