Math CHOP
Summary
The Math CHOP performs arithmetic operations on channels. The channels of a CHOP can be combined into one channel, and several CHOPs can be combined into one CHOP.
The OP page lets you preoperate on each sample, like making all samples positive or taking the square of each sample.
Using Combine Channels, for an input CHOP with multichannels, you can multiply the samples of one channel by the samples in the other channels, reducing N channels down to one. You can combine them by multiplying, adding, finding the maximum, etc..
Using Combine CHOPs, where there are two or more CHOP inputs, you can multiply (or add, etc.) the channels in one CHOP with the channels in all the other CHOPs, reducing N CHOPs to 1. (otherwise channels of multiinputs are just merged)
You can then postoperate on the resulting samples  negate, square root, etc.
Then using the MultAdd page it can offset and scale the values of each sample.
More conveniently you can use the Range page to do linear scaling as well by setting an output lowhigh range for a certain input lowhigh range.
Finally, you can round the resulting values off to an integer.
NOTE: To do logic operations (and, or, ...) between channels or CHOPs, use the Logic CHOP.
Contents
Parameters  OP Page
The four steps are performed in the following order:
Channel Pre OP preop
 ⊞  Unary operations can be performed on individual channels. A menu of unary operations (as described above) that are performed on each channel as it comes in to the Math CHOP include:
 Off
off
 Don't do anything to the channel.
 Negate
negate
 Take the negative value of each sample of the channel.
 Positive
pos
 Make negative values of the channel positive (absolute).
 Root
root
 Take the square root of all values in the channel.
 Square
square
 Square all the values in the channel.
 Inverse
inverse
 Take the inverse (1/x) of all values in the channel.
Combine Channels chanop
 ⊞  A choice of operations is performed between the channels of an input CHOP, for each input. The Nth sample of one channel is combined with the Nth sample of other channels:
 Off
off
 Don't combine the channels.
 Add
add
 Sum all the channels.
 Subtract
sub
 Subtract all the channels from the first.
 Multiply
mul
 Take the product of all the channels.
 Divide
div
 Divide the first channel by all the rest.
 Average
avg
 Take the average of all the channels.
 Minimum
min
 Take the minimum value of all the channels.
 Maximum
max
 Take the maximum value of all the channels.
 Length
len
 Assume the channels are a vector and compute its length.
Combine CHOPs chopop
 ⊞  A menu of operations that is performed between the input CHOPs, combining several CHOPs into one.
 Off
off
 Don't combine the channels.
 Add
add
 Sum all the channels.
 Subtract
sub
 Subtract all the channels from the first.
 Multiply
mul
 Take the product of all the channels.
 Divide
div
 Divide the first channel by all the rest.
 Average
avg
 Take the average of all the channels.
 Minimum
min
 Take the minimum value of all the channels.
 Maximum
max
 Take the maximum value of all the channels.
 Length
len
 Assume the channels are a vector and compute its length.
Channel Post OP postop
 ⊞  A menu (same as Channel Pre OP) is performed as the finale stage upon the channels resulting from the above operations.
 Off
off

 Negate
negate

 Positive
pos

 Root
root

 Square
square

 Inverse
inverse

Integer integer
 ⊞  The resulting values can be converted to integer. The Tscript ceil()
, floor()
and round()
expressions do the same.
 Off
off
 Don't affect the value.
 Ceiling
ceiling
 Round a value up to the next integer.
 Floor
floor
 Round a value down to the next integer.
 Round
round
 Round a value to the nearest integer.
Match by match
 ⊞  Match channels between inputs by name or number.
 Channel Number
index

 Channel Name
name

Align align
 ⊞  How to align channels from different inputs. See Align Option.
 Automatic
auto

 Extend to Min/Max
none

 Stretch to Min/Max
stretch

 Shift to Minimum
start

 Shift to Maximum
end

 Shift to First Interval
shift1

 Trim to First Interval
trim1

 Stretch to First Interval
stretch1

 Trim to Smallest Interval
trim

 Stretch to Smallest Interval
squash

Parameters  MultAdd Page
The three steps are next performed in the following order:
PreAdd preoff
 First, add the value to each sample of each channel.
Multiply gain
 Then multiply by this value.
PostAdd postoff
 Then add this value.
Parameters  Range Page
This is the final step prior to output.
From Range fromrange
 ⊞  Another way to multiply/add. Converts from one lowhigh range to another range.
fromrange1

fromrange2
To Range torange
 ⊞  Another way to multiply/add. Converts from one lowhigh range to another range.
torange1

torange2
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).
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.
Any of the procedural data operators. OPs do all the work in TouchDesigner. They "cook" and output data to other OPs, which ultimately result in new images, data and audio being generated. See Node.
TouchDesigner is a hierarchy of components. "root" is the topmost network in the hierarchy. The Path is simply /
. A typical path is /project1/moviein1
.
TouchDesigner's original builtin Command scripting language prior to Python.
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'.