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On 10/13/2010 9:33 PM, David Kastrup wrote:
KHMan writes:
Anyway most app developers do not need to code DCTs and FFTs

I find that C compilers tend to be actually astonishingly bad at that.
Coding the inner loops in assembly language can often halve the
execution time.  Somehow the optimizers/register allocators don't seem
to like complex butterflies all too well.


This was why I chose *specifically* DCT and FFT as a conversational gambit -- most widely-released mainstream implementations are still optimized in assembly language.

Mortals like me consume them in ready-made libraries. Would be interested to see what other scripting languages are doing in this respect.

A few hundred million ops per second doing them on Lua seemed far off enough that it seemed to me like a reasonable future target, but not something that can be currently done. Now since I was thinking only in terms of Lua, it seemed reasonable enough to me. Obviously, I am a horrid dunce.

Kein-Hong Man (esq.)
Kuala Lumpur, Malaysia