Re: Lower WAV pitch problem
Igor Kachan wrote:
> There was mail posted by Robert Craig to this list
> in 2001, dec 13, exactly with his EU fft program,
> try search on RDS site for this list archive.
>
> Rob was one of the developers of the Fourier
> programming language.
> Maybe, he will remember that times and tell us 
Well Igor, as a retired Russian submariner, I shouldn't tell
you too much , but one of the main uses of Fourier was
in submarine detection, i.e. analysing sonar signals.
In the mid-80's the Canadian navy hired a small
15-person company that I worked for to build a
compiler for an FFT machine they had built. It could
do FFT's faster than any other machine in the world.
It was designed from the ground up to do FFT's
using all kinds of parallelism. It had 8 independent pipelines,
and each pipeline had 7 stages. Imagine a factory where
there are 8 assembly lines and 7 workers in stages
on each line - one adds, the next multiplies, etc.
I've forgotten a lot since then, but I know that FFT's
(Fast Fourier Transforms) are important in
converting time-series data into the frequency domain,
i.e. extracting the frequency components from a signal.
Fourier, the programming language was based loosely on Ada,
the language that was trendy in the military back then.
I wasn't too proud of the language. My main fascination
was in compiling mathematical expressions into
machine instructions for this weird and very parallel machine.
It was important to order operations to take advantage of the
pipelines. A simple operation like adding two numbers meant
basically running an FFT but disabling a bunch of stuff.
The machine really wanted to do FFT's, and it wanted
all arrays to be powers of two etc. It was a painful
machine to program. The fact that there was any kind of
high-level language for it was somewhat impressive.
Later we sold a machine and a Fourier compiler
to MIT in the States for "Star Wars" research.
Uh Oh - I can hear the Royal Canadian Mounted Police
riding up to my door to take me away...
Regards,
Rob Craig
Rapid Deployment Software
http://www.RapidEuphoria.com
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