[PD] passing integers

Orm Finnendahl finnendahl at folkwang-hochschule.de
Thu Jan 17 13:11:36 CET 2002


thanx to miller and krzystof for the ideas!

Am Donnerstag, den 17. Januar 2002 um 12:03:24 Uhr (+0100) schrieb Krzysztof Czaja:
> hi,
> how about passing symbols, possibly written as somehow prefixed octal,
> hex or binary numbers, and then atoi()/strtol()/sscanf()/whatever()
> them to integers?

That's a very nice idea, but I think, I will end up using Millers
suggestion of passing lists of smaller integers instead, since that's
the way I used the object before anyway (see below).

> But I wonder:  if there was a huge amount of different masks generated
> during a Pd session, how this would affect the overall performance?
> What I mean is that the penalty of symbol hash table slot chaining
> could get high.
> If this is true, then I wonder:  is the above a viable reason for
> giving users a way (like sending a message to pd) to clear symbol
> table of currently unused (not bound, etc.) elements?

Yes, that would be definitely necessary, as the amount of generated
symbols would be immense.

The object, I'm needing it for is the markov object, I mentioned some
time ago. It stores elements in two data structures: (1.) A table,
implemented as linked list, which defines the succession of elements
and (2.) a correlated multidimensional search tree, which stores the
statistics of occurence of elements of the table in respect to markov
properties of any order. These statistics can for example be used to
generate new elements with probabilities which match the current state
of the table. The table can be extended by supplying elements to the
object from the outside world, or by the elements generated by the
object itself, it can be shrunk, manipulated etc...

The elements to be stored need to have the following properties:

- They have to be comparable not only for equality, but also, in
  special cases, whether they lie in a certain range (for example, if
  you code delta times of performers in real time performances, or if
  some properties of a complex event should not matter in respect of
  markov properties, but need to be stored within the element

- It should be possible to store an element with more than one
  dimension, for example if you want to store a chord progression
  including the velocities or delta times.

The idea, I came up with when I first wrote the object, was, to use
one 32-bit integer value internally for each element and define it as
up to 8 bitfields of variable (and userdefinable) width. In practice
that worked fine even with 32 bits, although sometimes problems arose
(like if you want to code 5 voice counterpoints including interval
structure, metrical weight, delta time and tie in information). It
would probably be nicest, to use pointers as reference to elements of
arbitrary type instead of integers since the 32 bit limitations could
be avoided. But then the user would have to provide a function which
tests for equality, and I have no idea, how this could be done within
the framework of pd.

I will probably end up using integers again internally (maybe 64 bits
instead of 32) and will send a list for storing each element which is
range checked, length checked and then converted into an integer. But
if someone has another idea, how to implement this, it would be
greatly appreciated. As I put in some work, I would really like, if
the object is considered useful by a lot of people and this is the
chance to have the object tailored to your own needs.


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