As long as we're discussing bugs in expr, I found a new one in the newly added "Avg" function in 0.56, I just sent a fix, see https://github.com/pure-data/pure-data/pull/287
2018-01-09 18:41 GMT-03:00 Charles Z Henry <[email protected]>: > > > On Jan 9, 2018 12:52 PM, "Alexandre Torres Porres" <[email protected]> > wrote: > > Hi list and Shahrokh. What do you think the output from factorial of > negative values? I read it's supposed to be minus infinity. Anyway, here's > a issue I'm reporting that factorial of negative values in [expr] output 0 > and freeze Pd for a while: https://github.com/pure-data/p > ure-data/issues/284 > > > The most consistent treatment would be to give it some value, other than > -inf, which will propagate into NaN's in other calculations. Otherwise, > outputs depend more on how denormals get handled rather than how Pd code is > written. Outputs could vary from system to system and that's just buggy. > > The factorial is generalized by the gamma function which has values at > non-zero and non-integer negative values, but it likely doesn't have much > practical use in Pd. You could write an external if it actually matters to > you for a project. > > So.... Since there's little point in being mathematically literal about > it, it's fine to just choose a value (0 or 1) for values less than 1. If > it's me, I would choose 1, so that factorial calculations have the same > value for bad inputs (values <1) as for the trivial input (=1). > > Chuck >
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