On Oct 17, 2:41=A0pm, Eric Jacobsen <eric.jacob...@[EMAIL PROTECTED]
> wrote:
> Dude, chill. =A0 I've no dog in this hunt, I'm merely pointing out that,
> just like with most things, there are some subtleties where one may
> have an advantage over the other given particular constraints. =A0 Is
> that so surprising? =A0 They're not identical, you know.
You initially claimed "some real advantages" for the FHT in terms of
"computing or memory resources," including "substantially smaller"
memory requirements. Whenever you were pressed for specifics about
these "subtleties," however, your examples turned out to be false.
False statements bother me, especially when you are repeating myths
that were debunked 20 years ago.
> Unless you want to claim that an FFT always provides a superior
> implementation op****tunity compared to an FHT under all possible
> cir***stances I don't think there's an argument here.
I made no such claim. I stated repeatedly that they are (as far as is
currently known) almost identical with respect to memory usage
(including access patterns), arithmetic, and organization/structure.
Old claims that one has a substantial performance advantage over the
other have been repeatedly disproved in the literature.
> There are times when an obscure tool or technique can provide an
> advantage. =A0 Being aware of the obscure tools and the differences
> allows that to be part of the tradeoff space. =A0
Repeating long-debunked myths about obscure tools does not help people
to understand them better.
The DHT certainly has some interesting properties, and is a nice
transform to think about from time to time. (For example, in one of
our own papers we showed that DHTs give a simple way to apply Rader's
algorithm for prime-length transforms to purely real data, although
Burrus in 1982 showed that there is a way to do this directly for real-
data FFTs too.) But early claims of significant performance or memory
advantages from FHT algorithms for power-of-two sizes have, sadly, not
withstood the test of time.
Regards,
Steven G. Johnson
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