DEC64

oy implementations, at worst dangerous (in the sense that they may provide wildly inaccurate results, due to convergence Re 3: agreed. Though there is still a gargantuan number of values which have 2 or more representations, and that makes all kinds of comparisons more complicated. Dealing with that efficiently in SW is difficult, and more so in HW. It might be worth it if the advantages outweigh it, but at least I personally don't see it. Re 4: if it can be "undoubtedly improved with effort", why hasn't it been done in several years? Sure, it may be possible, but I will keep my doubts for the time being :-) I agree with you on 5, 6 and 7.

en more: https://github.com/douglascrockford/DEC64/blob/master/dec64.... For most comparisons (no, comparing numbers with the same exponent is not the norm) it will take around FIFTY INSTRUCTIONS TO CHECK IF TWO NUMBERS ARE EQUAL OR NOT. Many of these instructions are branches – and inherently unpredictable ones at that, which means that pipeline stalls will be normal. All told, I would expect equality comparison to typically take around 100 cycles. It's not even clear to me that this implementation is correct because at the end of the subtraction, it compares the result to the zero word, which is only one of the 255 possible representations of zero. The lack of a single canonical representation of any number is just as bad for other arithmetic operations and comparisons, if not worse. Crockfords bugaboo with IEEE 754 floating-point is bizarre, verging on pathological. He devoted a section in his book "JavaScript: The Good Parts" to a rather ill-informed rant against it. When I saw him give a talk, I took the opportunity to ask him what he thought would be a good alternative to using IEEE 754. His answer was – I shit you not – "I don't know". Apparently this proposal is the answer. No thanks, I will stick with the amazingly successful, ubiquitous, thoroughly thought out standard, that was spearheaded by William Kahan – one of the greatest numerical analysts of all time. Anyone who doesn't appreciate how good we have it with IEEE 754 should really read "An Interview with the Old Man of Floating-Point" [1], in which Kahan relates just how messed up this stuff was before the IEEE 754 standardization process. It should also be noted that there already is an IEEE standard for decimal floating-point [2], which is not only infinitely better thought out than this drivel, but also is already implemented in hardware on many systems sold by IBM and others, specifically for financial applications. [1] http://www.cs.berkeley.edu/~wkahan/ieee754status/754story.ht... [2] http://en.wikipedia.org/wiki/Decimal64_floating-point_format