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Re: [Scheme-reports] Proposed language for 'eqv?' applied to inexact real numbers
Ray Dillinger scripsit:
> NaN is NOT A NUMBER, and the question of its numeric
> equivalence to anything does not make sense. The question
> is a category error and therefore both the "true" answer
> and the "false" answer are meaningless.
Sometimes, but not always. Thus, 0/0 and infinity - infinity are
not "no real number at all" (as sqrt(-2) is) but "any real number
at all". Furthermore, two branches of a computation that are to be
compared for equality may both generate NaN, but for entirely different
reasons. Since = is a conservative approximation to equality, it's
correct for NaN=Nan to return false, meaning "no match".
John Cowan cowan@x http://ccil.org/~cowan
Big as a house, much bigger than a house, it looked to [Sam], a grey-clad
moving hill. Fear and wonder, maybe, enlarged him in the hobbit's eyes,
but the Mumak of Harad was indeed a beast of vast bulk, and the like of him
does not walk now in Middle-earth; his kin that live still in latter days are
but memories of his girth and his majesty. --"Of Herbs and Stewed Rabbit"
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