Re: Peculiar floating point numbers in GCC
On Apr 7, 7:38 pm, Walter Bright <wal...@digitalmars-nospamm.com>
wrote:
James Kanze wrote:
The problem is that if you want to analyse your limits in
detail, you don't really know what precision is being used.
There are two schools of thought here, and I don't know enough
numerics to have an opinion as to which is right. (The only
calculations in my present application involve monetary amounts,
so still another set of rules applies:-).)
My experience in the matter is that the only algorithms that failed when
used with greater precision were:
1) test suites
2) wrong for other reasons, too
Put another way, if I was implementing a square root algorithm, why
would I ever *need* less accuracy?
I'm sure that that is true for many algorithms. But the
question isn't more or less accuracy, it is known accuracy, and
I can imagine certain algorithms becoming instable if the
accuracy varies.
As I said, I don't know the domain enough to have an opinion. I
do know that in my discussions with experts in the domain,
opinions varied, and many seem to consider the extended accuracy
in the Intel processors a mis-design (or maybe I've
misunderstood them). Curiously, all seem to consider the base
16 used in IBM mainframe floating point bad thing, and the most
common reason they give is the varying accuracy.
--
James Kanze (Gabi Software) email: james.kanze@gmail.com
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