expr, expr~, fexpr~
syadegar at man104-1.ucsd.edu
Tue Dec 12 01:13:58 CET 2000
Two new objects expr~ and fexr~, which are extensions of expr:
You can obtain a version from:
This version has a number of expr bug fixes as well.
I'll appreciate hearing about bugs, comments, suggestions, etc.
Shahrokh Yadegari (sdy at ucsd.edu)
Here is the README file:
The object "expr" is used for expression evaluaion of control data.
Expr~ and fexpr~ are extentions to the expr object to work with vectors.
The expr~ object is designed to efficiently combine signal and control
stream processing by vector operations on the basis of the block size of
NOTE: Functions in expr~ do not support vectors yet. I am working on
The fexpr~ object provides a flexible mechanism for building FIR and IIR
filters by evaluating expressions on a sample by sample basis and
providing access to prior samples of the input and output audio streams.
When fractional offset is used, fexpr~ uses linear interpolation to
determine the value of the indexed sample.
The three objects expr, expr~, and fexpr~ are implemented in the
same object so the files expr~.pd_linux and fexpr~.pd_linux are links to
Here are some syntax information: (refer to help-expr.pd for examples)
The syntax is very close to how expression are written in
C. Variables are specified as follows where the '#' stands
for the inlet number:
$i#: integer input variable
$f#: float input variable
$s#: symbol input variable
Used for expr~ only:
$v#: signal (vector) input (vector by vector evaluation)
Used for fexpr~ only:
$x#[n]: the sample from inlet # indexed by n, where n has to
satisfy 0 => n >= -vector size,
($x# is a shorthand for $x#, specifying the current sample)
$y[n]: the output value indexed by n, where n has to
satisfy 0 > n >= -vector size,
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