Math CHOP
Summary[edit]
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.
Tip: Customizing each channel:: You can use the local member chanIndex
in a parameter like PostAdd, for example, me.chanIndex*2
to give a different postadd value for each channel. chanIndex
is available in numerous CHOPs like the Pattern CHOP. (expressions are nonoptimized)
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
 Multiply 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
 Multiply 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

Match by match
 ⊞  Match channels between inputs by name or index.
 Channel Number
index

 Channel Name
name

Align align
 ⊞  This menu handles cases where multiple input CHOPs have different start or end times. All channels output from a CHOP share the same start/end interval, so the inputs must be treated with the Align Options:
 Automatic
auto
 It will trim to the current Time Slice if there are any Time Slices, else it will do an Extend Min/Max.
 Extend to Min/Max
none
 Find the earliest start and latest end, and extend all inputs to that range using the extend conditions. (see Extend Conditions).
 Stretch to Min/Max
stretch
 Find the earliest start and latest end, and stretch every channel's start and end to that range.
 Shift to Minimum
start
 Find the earliest start and shift all channels so they all start at that index. All channels are extended to the length of the longest one.
 Shift to Maximum
end
 Find the latest end and shift all channels so they all end at that index. Extend all channels to the length of the longest one.
 Shift to First Interval
shift1
 Shift all channels to the start of the first CHOP and sample all inputs using the first input's range.
 Trim to First Interval
trim1
 Trim all channels to first CHOP's range.
 Stretch to First Interval
stretch1
 Stretch all channels to the first CHOP's range.
 Trim to Smallest Interval
trim
 Trim all channels to the smallest start/end interval. The start and end values may not come from the same channel.
 Stretch to Smallest Interval
squash
 Stretch all channels to the smallest start/end interval. The start and end values may not come from the same channel.
Interp Pars per Sample interppars
 Use this option when the input is a higher frequency than the timeline (example: audio). It will avoid any pops or crackles in the output when adjusting the multiply, add or range parameters.
Integer integer
 ⊞  The resulting values can be converted to integer.
 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.
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).
Operator Inputs
 Input 0 
Info CHOP Channels
Extra Information for the Math CHOP can be accessed via an Info CHOP.
Common CHOP Info Channels
 start  Start of the CHOP interval in samples.
 length  Number of samples in the CHOP.
 sample_rate  The samplerate of the channels in frames per second.
 num_channels  Number of channels in the CHOP.
 time_slice  1 if CHOP is Time Slice enabled, 0 otherwise.
 export_sernum  A count of how often the export connections have been updated.
Common Operator Info Channels
 total_cooks  Number of times the operator has cooked since the process started.
 cook_time  Duration of the last cook in milliseconds.
 cook_frame  Frame number when this operator was last cooked relative to the component timeline.
 cook_abs_frame  Frame number when this operator was last cooked relative to the absolute time.
 cook_start_time  Time in milliseconds at which the operator started cooking in the frame it was cooked.
 cook_end_time  Time in milliseconds at which the operator finished cooking in the frame it was cooked.
 cooked_this_frame  1 if operator was cooked this frame.
 warnings  Number of warnings in this operator if any.
 errors  Number of errors in this operator if any.
TouchDesigner Build:
CHOPs 

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