OpenMusic Reference
x->dx
x->dx
(series module) -- returns a list of the intervals between values of a list
Syntax
x- >dx self
Inputs
| name | data type(s) | comments |
|---|---|---|
| self | a list |
Output
| output | data type(s) | comments |
|---|---|---|
| first | a list of intervals |
Description
This function is the complement of dx->x
x->dx takes its name from the mathematical notation for the change over time in a given quantity. This change in time is usually symbolized by the greek letter delta: Δ. It is also notated with a d and the variable whose change over time is being measured, frequently x , i.e. dx.
x->dx finds the relative change between each pair of values in self . The list returned will thus have one less element than the list input.
Examples
Calculating the delta of a number series
This number series will return:
? OM->(4 1 4 -3 -4 1 0)
Calculating the intervals in a melody
The Chord-seq at the top is passed through flat in order to get rid of nesting and turn it into a flat list of midics. x->dx returns (300 100 100 200 400) , which is divided by 100 to yield the number of semitones between each note:
? OM->(3 1 1 2 4)
This melody is reconstructed in the example for dx->x
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