At 12:47 AM 4/21/01 -0400, Allison Parent wrote: Yes, they are three different things. Range is not in question here (which is determined mostly by the exponent and base of the exponent). So we are left with accuracy and resolution (back in high school I was taught the terms accuracy and precision.). I don't know how your (accurate) statement clarifies the matter at hand. I claim that a floating point representation specifies precision and has nothing to say about accuracy (other than accuracy is limited by precision). To clarify, say a number is 175.136985. This represents my weight very precisely, but whether it is accurate or not is a different matter. Again, I must be missing something, or perhaps it is a definitional thing. I've given my definition for precision (or what you call resolution) and accuracy. I claim accuracy is largely outside the scope of a number representation. Perhaps you and others have a different definition than I do and are also internally consistent. I'd like to hear it, since I keep running into it and don't understand it. As for truncation, this is exactly the example I give below. 0.1 (decimal) is a non-repeating fraction in binary, and so might show up as 0.09999999999999 when converted back to a decimal output string. It is very conveniently and exactly representable in BCD and so won't suffer this type of problem. This is kind of unfair, because it just so happens that this example has chosen a number that matches the base. Also, although it might look wickedly different from 0.1, the error is only 10^-14. If, on the other hand, you want to know what is sin(0.1), I claim the binary representation is more precise (and thus allows more accuracy; accuracy here depends on the implementation of the trig algorithms and not inherently in the number system). The counter example is that 0.11111 (base 16) [that is, 2^-4 + 2^-8 + 2^-12 + 2^-16 + 2^-20] is exactly representable in a binary number system, but not in an 8B BCD number representation because there isn't enough precision to hold all the digits. nope, I didn't mean that at all. maybe I should give up and take this to the alt.ieee.vs.bcd.floating-point newsgroup. :-) ----- Jim Battle == frustum(a)pacbell.net