[PD-dev] pvoc example and rsqrt~

Thomas Grill t.grill at gmx.net
Mon Dec 29 00:53:03 CET 2003


Hi Miller, hi all,

i came across a strange thing when testing the Altivec SIMD 
implementation with my favorite example, namely 04.fft/09.pvoc.pd .
It seems that the phase propagation is dependent on the fact that 
rsqrt~ (0) delivers a valid non-zero value of about 1.e+19. (well, 
which non-zero value is irrelevant)
If rsqrt~ (0) = 0, which would make more sense to me (given the zero 
checks in /~ ) the example is silent. (what almost drove me nuts, btw. 
)

Although i already asked before, i'd be interested about the common 
behaviour of objects that are endangered to deliver NANs. Should these 
cases always be trapped and bashed to zero? To know that would help me 
a lot with the proper SIMD implementation.

best greetings,
Thomas





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