Function CHOP
Summary[edit]
The Function CHOP provides more complicated math functions than found in the Math CHOP : trigonometic functions, logarithmic functions and exponential functions, and also audio decibels (dB)poweramplitude conversions.
Most of the functions require only one parameter, and they are applied as a unary operator to each input channel. Some functions take two parameters, and these require the use of the second input. The first parameter, X, is always a value from a channel in the first input. The second parameter, Y, is a value from a corresponding channel in the second input. Channels from each input are paired by name or index.
Since many of these functions can produce math errors, an error handling tab is provided for error handling and recovery. Errors can be handled by replacing the bad sample with a predefined value or by using the value of the previous sample. Alternatively, cooking can be aborted upon error for debugging networks.
Contents
Parameters  Function Page
Function func
 ⊞  Which math function to apply to the channels. All of the functions are unary functions except for the binary functions 'arctan (Input1/Input2)' and 'Input1 ^ Input2'. In the cases of power functions, a negative base is inverted first to avoid imaginary numbers, and the result is negated.
 sqrt(x) Square Root
sqrt
 Square Root of Input 1.
 abs(x) Absolute Value
abs
 Absolute Value of Input 1.
 sign(x) Sign
sign
 Sign of Input 1.
 cos(x) Cosine
cos
 Cosine of Input 1.
 sin(x) Sine
sin
 Sine of Input 1.
 tan(x) Tangent
tan
 Tangent of Input 1.
 acos(x) Arccosine
acos
 Arccosine of Input 1.
 asin(x) Arcsine
asin
 Arcsine of Input 1.
 atan(x) Arctan( Input1 )
atan
 Arctan of Input 1.
 atan2(y,x) Arctan( Input1 / Input2 )
atan2
 Arctan of (Input 1 / Input 2).
 cosh(x) Hyperbolic Cosine
cosh
 Hyperbolic Cosine of Input 1.
 sinh(x) Hyperbolic Sine
sinh
 Hyperbolic Sine of Input 1.
 tanh(x) Hyperbolic Tangent
tanh
 Hyperbolic Tangent of Input 1.
 log10(x) Log base 10
log
 Log base 10 of Input 1.
 logN(x) Log base N
logb
 Log base Base Value of Input 1.
 ln(x) Natural Log
ln
 Natural Log of Input 1.
 pow(10,x) 10 ^ Input1
pow10
 10 to the power of Input 1.
 exp(x) e ^ Input1
exp
 e to the power of Input 1.
 pow(x) Base ^ Input1
powe
 Base value to the power of Input 1. If Base value is negative result is ((Base Value) ^ Input 1)
 pow(x) Input1 ^ Exponent
powb
 Input 1 to the power of Exponent value. If Input 1 is negative result is ((Input 1) ^ Exponent Value).
 pow(x,y) Input1 ^ Input2
pow
 ((Input 1) ^ Input 2)
 dB to Power
dbtopower
 Decibel (Input 1) to amplitude.
 Power to dB
powertodb
 Amplitude (Input 1) to decibel.
 dB to Amplitude
dbtoamp
 Decibel (Input 1) to amplitude.
 Amplitude to dB
amptodb
 Amplitude (Input 1) to decibel.
Base Value baseval
 The value of the base for 'Log base N' and 'Base ^ Input1'. parameter name /baseval
Exponent Value expval
 The value of the exponent for 'Input1 ^ Exponent'
. channel name /expval
Angle Units angunit
 ⊞  For trigonometric functions, the angles can be measured in Degrees, Radians, or Cycles (0 to 1).
 Degrees
deg

 Radians
rad

 Cycles
cycle

Match by match
 ⊞  How to pair channels together from the two inputs for the binary functions, by name or by channel index.
 Channel Number
index

 Channel Name
name

Parameters  Error Page
Error Handling error
 ⊞  How to correct samples with math errors:
 Abort With Error Message
abort
 Cooking aborts.
 Replace With Specified Values
replace
 Values specified below.
 Use The Previous Value
useprev
 Uses the last good result.
+ Infinity Value pinfval
 Value to use when an infinity error occurs. Caused by sinh(), cosh() and tan().
 Infinity Value ninfval
 Value to use when a negative infinity error occurs. Caused by sinh() and tan().
Domain Error Value domval
 Value to use when a domain error occurs. Caused by asin(), acos(), log10(), logN(), ln() and sqrt().
Divide Error Value divval
 Value to use when a divide by zero error occurs. Caused by pow(x,y).
Parameters  Common Page
Time Slice timeslice
 Turning this on forces the channels to be "Time Sliced". A Time Slice is the time between the last cook frame and the current cook frame.
Scope scope
 To determine which channels get affected, some CHOPs use a Scope string on the Common page.
Sample Rate Match srselect
 ⊞  Handle cases where multiple input CHOPs' sample rates are different. When Resampling occurs, the curves are interpolated according to the Interpolation Method Option, or "Linear" if the Interpolate Options are not available.
 Resample At First Input's Rate
first
 Use rate of first input to resample others.
 Resample At Maximum Rate
max
 Resample to the highest sample rate.
 Resample At Minimum Rate
min
 Resample to the lowest sample rate.
 Error If Rates Differ
err
 Doesn't accept conflicting sample rates.
Export Method exportmethod
 ⊞  This will determine how to connect the CHOP channel to the parameter. Refer to the Export article for more information.
 DAT Table by Index
datindex
 Uses the docked DAT table and references the channel via the index of the channel in the CHOP.
 DAT Table by Name
datname
 Uses the docked DAT table and references the channel via the name of the channel in the CHOP.
 Channel Name is Path:Parameter
autoname
 The channel is the full destination of where to export to, such hasgeo1/transform1:tx
.
Export Root autoexportroot
 This path points to the root node where all of the paths that exporting by Channel Name is Path:Parameter are relative to.
Export Table exporttable
 The DAT used to hold the export information when using the DAT Table Export Methods (See above).
Operator Inputs
 Input 0 
 Input 1 
CHOPs 

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An Operator Family which operate on Channels (a series of numbers) which are used for animation, audio, mathematics, simulation, logic, UI construction, and many other applications.
TouchDesigner is a hierarchy of components. "root" is the topmost network in the hierarchy. The Path is simply /
. A typical path is /project1/moviein1
.
A Time Slice is the time from the last cook frame to the current cook frame. In CHOPs it is the set of short channels that only contain the CHOP channels' samples between the last and the current cook frame.
A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator.
samplespersecond of a CHOP. Each CHOP in your network has a sample rate, whether it is used or not. The overall timeline has a "frame rate", which is the number of animation frames per second, generally your monitor display frequency.
Exporting is the connection of CHOP channels to parameters of operators. The output of each exporting CHOP is one or more channels, active only while the CHOP Viewer is on. The current value of a channel can be exported to a parameter of any operator, overriding that parameter's value. See Parameter.
An Operator Family that manipulates text strings: multiline text or tables. Multiline text is often a command Script, but can be any multiline text. Tables are rows and columns of cells, each containing a text string.
Parameters in TouchDesigner are an operator's settings (numbers, menus, flags, strings, paths) which the user can alter. Parameters for any operator can be opened by rightclicking on the operator and selecting "Parameters..." A currently selected operator's parameters can be viewed in a Network Editor by pressing the keyboard shortcut 'p'.