Math CHOP

The Math CHOP is the workhorse for combining and remapping numerical data. It handles per-channel functions, channel-to-channel arithmetic, multi-input arithmetic, and linear range remapping in a single op. If you find yourself reaching for a Constant + a multiply + a clamp, a single Math CHOP almost always does it more cleanly.

The OP Page

The OP page is where most of the work happens. It runs in a fixed order: pre-op (per-channel) → combine channels → combine CHOPs → post-op.

Parameter	Options	What it does
Channel Pre OP	Off, Negate, Positive, Root, Square, Inverse	Per-channel function applied first
Combine Channels	Off, Add, Subtract, Multiply, Divide, Average, Minimum, Maximum, Length	Combine the channels within one CHOP into one
Combine CHOPs	Off, Add, Subtract, Multiply, Divide, Average, Minimum, Maximum, Length	Combine across multiple input CHOPs
Channel Post OP	Off, Negate, Positive, Root, Square, Inverse	Per-channel function applied last
Match by	Channel Number, Channel Name	How channels from multiple inputs are paired
Align	Automatic, Extend to Min/Max, Stretch, Shift, Trim (multiple variants)	How to handle inputs with differing start/end times
Integer	Off, Ceiling, Floor, Round	Cast result to integer with the chosen rounding rule

Mult-Add Page

A linear scaling step that runs after the OP page work. Equivalent to out = (x + preoff) * gain + postoff.

Parameter	What it does
Pre-Add	Add this value to each sample before multiplying
Multiply	Scale the sample (the most-used parameter on this page)
Post-Add	Add this value after multiplying

Range Page

Linear remap from one range to another. Useful any time the natural range of a signal doesn’t match what the consumer wants.

Parameter	What it does
From Range	The expected low/high of the incoming data (e.g. -1 to 1 from an LFO)
To Range	The desired low/high of the output (e.g. 0 to 360 for a rotation)

Practical Example: LFO into Geo Rotation

lfo1 (Sine, default range -1..1)
   ↓
math1 (Range: From -1 to 1, To 0 to 360)
   ↓
[exported into geo1.par.Rry]

The LFO’s natural ±1 swings become a 0-to-360 degree spin without any expression math.

Common Patterns

• Normalize MIDI velocity. From Range 0..127, To Range 0..1.
• Remap normalized to color. From Range 0..1, To Range 0..255 for an 8-bit color channel.
• Sum a vector. Combine Channels = Length on a 3-channel CHOP gives the magnitude (sqrt of sum of squares).
• Average channels. Combine Channels = Average on a multi-channel CHOP gives a one-channel mean.
• Difference between two CHOPs. Combine CHOPs = Subtract on two single-channel inputs gives a - b.

Common Gotchas

• From Range vs To Range direction. Mapping From 0..1 To 100..0 is a valid inversion; the result decreases as input increases. The Range page does not clamp by default; values outside From Range extrapolate linearly.
• Combine CHOPs with mismatched channel counts. If one input has tx ty tz and another has just tx, “Match by Channel Number” pairs the first three positionally; “Match by Channel Name” only acts on tx and leaves ty tz from the larger input alone.
• Combine Channels collapses to one channel. Once Combine Channels is set, the output of that step is a single channel. Channel naming preserves the first input’s name.
• Pre OP and Post OP both run. They aren’t either/or; you can square (Pre OP) and then negate (Post OP) for -x².

Related Nodes

• Constant CHOP: typed-in values to feed into the math
• LFO CHOP: the most common time-varying input
• Noise - CHOP and TOP: organic randomness as input
• Select CHOP: pick the channels you want to math against

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(y-) Next Page: Noise - CHOP and TOP

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