Re: [Discuss-gnuradio] Bug in gr_quadrature_demod_cf, or scheduler?

[Robert McGwier]

When I wrote a fast atan table look algorithm a long time ago ( and I 
have no recollection if our stuff traces its ancestry to that or not) I 
picked the table size for my problem at the time.  There is a large 
speed up using the table lookup algorithm even on today's machines but 
there is no reason we can't increase the size of the table to get a 
better approximation and the theoretical speed will be the same but with 
decreased average error.  The trade off is that the table becomes very 
large as you demand higher accuracy.  We could in fact make the error 
demand an input and compute the table on set up.

Things to think about when you are otherwise indisposed.  ;-).

Bob



Johnathan Corgan wrote:
> Steven Clark wrote:
>
> > Do you have a sense of how much slower the regular atan2f function is
> > than gr_fast_atan2f?
>
> I don't think there were any formal benchmarks done, but IIRC the fast
> atan2 reduced CPU utilization by a factor of 5 for a WFM demodulator.


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