e85d191b46
- merge v0.01 --> Añadido fileselector - Añadidas fuentes de Gem y Pure Data - pix2jpg incluído en Gem. Archivos de construcción de Gem modificados. - Añadido fichero ompiling.txt con instrucciones de compilación
97 lines
3.5 KiB
Text
97 lines
3.5 KiB
Text
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You can get more information on the expr object at
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http://www.crca.ucsd.edu/~yadegari/expr.html
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-----------
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New if Version 0.4
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-access to variables (made by value object)
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-multiple expression separated by ;
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-added the following shorthands:
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$y or $y1 = $y1[-1] and $y2 = $y2[-1]
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-new functions:
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if - conditional evaluation
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cbrt - cube root
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erf - error function
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erfc - complementary error function
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expm1 - exponential minus 1,
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log1p - logarithm of 1 plus
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isinf - is the value infinite,
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finite - is the value finite
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isnan -- is the resut a nan (Not a number)
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copysign - copy sign of a number
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ldexp - multiply floating-point number by integral power of 2
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imodf - get signed integral value from floating-point number
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modf - get signed fractional value from floating-point number
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drem - floating-point remainder function
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Thanks to Orm Finnendahl for adding the following functions:
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fmod - floating-point remainder function
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ceil - ceiling function: smallest integral value not less than argument
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floor - largest integral value not greater than argument
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------------
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New in Version 0.3
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-Full function functionality
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------------
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The object "expr" is used for expression evaluaion of control data.
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Expr~ and fexpr~ are extentions to the expr object to work with vectors.
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The expr~ object is designed to efficiently combine signal and control
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stream processing by vector operations on the basis of the block size of
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the environment.
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fexpr~ object provides a flexible mechanism for building FIR and
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IIR filters by evaluating expressions on a sample by sample basis
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and providing access to prior samples of the input and output audio
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streams. When fractional offset is used, fexpr~ uses linear interpolation
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to determine the value of the indexed sample. fexpr~ evaluates the
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expression for every single sample and at every evaluation previous
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samples (limited by the audio vector size) can be accessed. $x is used to
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denote a singnal input whose samples we would like to access. The syntax
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is $x followed by the inlet number and indexed by brackets, for example
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$x1[-1] specifies the previous sample of the first inlet. Therefore,
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if we are to build a simple filter which replaces every sample by
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the average of that sample and its previous one, we would use "fexpr~
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($x1[0]+$x1[-1])/2 ". For ease of when the brackets are omitted, the
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current sample is implied, so we can right the previous filter expression
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as follows: " fexpr~ ($x1+$x1[-1])/2". To build IIR filters $y is used
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to access the previous samples of the output stream.
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The three objects expr, expr~, and fexpr~ are implemented in the same object
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so the files expr~.pd_linux and fexpr~.pd_linux are links to expr.pd_linux
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This release has been compiled and tested on Linux 6.0.
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--------
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Here are some syntax information: (refer to help-expr.pd for examples)
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Syntyax:
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The syntax is very close to how expression are written in
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C. Variables are specified as follows where the '#' stands
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for the inlet number:
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$i#: integer input variable
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$f#: float input variable
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$s#: symbol input variable
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Used for expr~ only:
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$v#: signal (vector) input (vector by vector evaluation)
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Used for fexpr~ only:
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$x#[n]: the sample from inlet # indexed by n, where n has to
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satisfy 0 => n >= -vector size,
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($x# is a shorthand for $x#[0], specifying the current sample)
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$y#[n]: the output value indexed by n, where n has to
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satisfy 0 > n >= -vector size,
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$y[n] is a shorthand for $y1[n]
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I'll appreciate hearing about bugs, comments, suggestions, ...
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Shahrokh Yadegari (sdy@ucsd.edu)
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7/10/02
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