[PD] Wave Shaping

[Frank Barknecht]

Hallo,
zmoelnig at iem.at hat gesagt: // zmoelnig at iem.at wrote:

> Zitiere Phillip Stearns <mindphone_divided at yahoo.com>:
> 
> > Thanks for the tip!  So is general rule to avoid realtime expr~ objects
> > if at all possible in the future?
> > 
> 
> i would have thought though some months ago, but matiu and tim taught me better.
> 
> [expr~] is a very useful and fast object (it is not slower than writing the
> maths in pd) (to know this would have saved me a _lot_ of patching in the past)

In this case of waveshaping it's definitly not the expr~ object,
that's slow, but the evaluation of the formula, which is pre-processed
in the tabread4~ case. tabread4~ is just doing something entirely
different than expr~ does in this application. 

BTW: You should be able to let expr~ do practically the same as
tabread4~ by using the array-accessing lookup instructions available
to all expr-objects like in:

[expr array100[$f1]]

Add to this a formula for 4-point polynomial interpolation as
described in [1] and you can replace tabread4~ with expr-objects. And
do the benchmark again!  ;)

[1] Miller's book:
http://www.crca.ucsd.edu/~msp/techniques/latest/book-html/node27.html

Ciao
-- 
 Frank Barknecht                               _ ______footils.org__