I am not sure where it is orbiting
There is a concept called significance
knowing the limitations of an algorithm such as it uses double
precision floating point numbers means that is as precise as it gets
there are other possibilities such as IEEE quadruple-precision
floating-point data type "quadruple" (128 bits or 16 bytes).
Do you think there is value in knowing whether something is
calculated with single, double, quadruple precision?
If it is all the same to you then don't worry if it is not all the
same to me.
Donna
[EMAIL PROTECTED]
On 26-Jun-06, at 2:04 PM, Don Guinn wrote:
John, isn't this whole thread revolving around what is a correct
value? To me it looks like a good part of this discussion revolve
around many J primitives converting to double precision floating
point resulting in a loss of precision. Are you defining a
calculation as "correct" if the result is the closest number
representable in a double precision floating point number to the
result if calculated in infinite precision? This may not be
sufficient in some calculations. But that's as good as it gets in
most programming languages and is usually more than adequate. The
problem is that it is not always adequate. And that's as you say,
it's a numerical analysis question.
Perhaps the possible coming of arbitrary precision numbers (or
whatever they're called) in J might address many of the concerns in
this thread.
John Randall wrote:
As I mentioned in an early post, you can assume that J library
functions
return correct values. As soon as you manipulate them in any way,
it is
your algorithm. My prior example showed how even + can be ill-
behaved. An I/O logical analyzer is not going to help: it's a
numerical analysis
question.
Best wishes,
John
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