Available Tendencies¶

This document describes the different types of tendencies available in the Waveform Editor and the parameters you can set for each in the YAML configuration.

Each tendency defines the behavior of the signal over a specific time interval. You can chain multiple tendencies together to create complex waveforms.

Common Time Parameters¶

Most tendencies accept the following parameters to define their time interval. You can provide the following three parameters. If only two are provided, the third is calculated automatically (start + duration = end). If all three are provided, they must be consistent.

start: The absolute time at which the tendency begins. If omitted, it defaults to the end time of the previous tendency, or 0 if it's the first tendency.
duration: The length of time the tendency lasts. If omitted, it defaults to 1.0 second (unless start and end are given). Must be positive.
end: The absolute time at which the tendency ends. If omitted, it's calculated from start + duration.

Note

The Piecewise Linear Tendency is an exception and derives its time interval solely from its time parameter list. It does not accept start, duration, or end.

Constant Tendency¶

Represents a constant value over the specified time interval.

Parameters¶

value: The constant value the signal holds during this tendency. If omitted, it defaults to the last value of the previous tendency, or 0 if it's the first tendency.
start, duration, end: See Common Time Parameters.

- {type: constant, value: 3, start: 3, duration: 10}

If the value is not specified, it will be set to the last value of the previous tendency. For example:

Example plot of a Constant Tendency without a value

- {type: linear, to: 3, duration: 10}
- {type: constant, duration: 10}

Linear Tendency¶

Represents a linear change in value (increase or decrease) over the specified time interval. The line is defined by its start value, end value, and rate of change, related by to = from + rate * duration.

Parameters¶

from: The value at the start of the tendency. If omitted, it defaults to the last value of the previous tendency (or 0 if first tendency), unless to and rate are provided.
to: The value at the end of the tendency. If omitted, it defaults to the first value of the next tendency if that value is explicitly set by the user, otherwise defaults to the calculated from value (implying a rate of 0), unless from and rate are provided.
rate: The rate of change (slope) of the signal during this tendency. If omitted, it's calculated from from and to.
start, duration, end: See Common Time Parameters.

- {type: linear, from: 3, to: 8, duration: 10}

If the from or to values are not specified, they will be taken from the adjacent tendencies. For example:

Example plot of a Linear Tendency, showing the use of adjacent tendencies for missing values

- {type: constant, value: 3, duration: 10}
- {type: linear, duration: 10}
- {type: constant, value: 10, duration: 10}

Warning

Providing inconsistent from, to, and rate values (where from + rate * duration != to) will result in an error. For example:

- {type: linear, from: 3, to: 5, rate: 2, duration: 10}

Smooth Tendency¶

Represents a smooth transition between the end of the previous tendency and the start of the next tendency using a cubic spline. This ensures that the value and the derivative (rate of change) are continuous at the boundaries between smooth tendencies and their neighbours.

Parameters¶

from: The value at the start of the tendency. If omitted, it defaults to the last value of the previous tendency (or 0 if first tendency).
to: The value at the end of the tendency. If omitted, it defaults to the first value of the next tendency if that value is explicitly set by the user, otherwise defaults to the calculated from value.
start, duration, end: See Common Time Parameters.

- {type: linear, from: 3, to: 8, duration: 10}
- {type: smooth, duration: 10}
- {type: linear, from: 5, to: 1, duration: 10}

Note

The start and end derivatives are automatically set to match those of adjacent tendencies.

Repeat Tendency¶

Repeats a defined sequence of inner tendencies (a sub-waveform) multiple times. Optionally the period/frequency can be provided to stretch or compress the time-axis of the waveform to match the specific frequency.

Parameters¶

waveform: A list defining the sequence of tendencies to be repeated. This follows the same format as the main waveform definition. The start time of the first tendency must be 0.
frequency: The number of repetitions of the inner waveform per unit time. Must be positive.
period: The duration assigned to one full repetition of the inner waveform. Must be positive.
start, duration, end: See Common Time Parameters. These define the total interval over which the repetition occurs.

- type: repeat
  duration: 30
  waveform:
  - {type: constant, value: 1, duration: 3}
  - {type: linear, from: 1, to: 2, duration: 3}
  - {type: smooth, duration: 5}

If you want to keep the same repeated waveform as above, but would like to set the period of the repetition to be exactly 10 seconds, you can use the period or frequency parameter, for example:

Example plot of a Repeat Tendency with a set period

- type: repeat
  duration: 30
  period: 10
  waveform:
  - {type: constant, value: 1, duration: 3}
  - {type: linear, from: 1, to: 2, duration: 3}
  - {type: smooth, duration: 5}

Piecewise Linear Tendency¶

Defines a sequence of points connected by straight lines.

Parameters¶

time: A list of time points. Must be strictly monotonically increasing and must have at least 1 point.
value: A list of corresponding values at each time point in the time list. Must have the same length as time.

Example plot of a Piecewise Linear Tendency

- {type: piecewise, time: [0,1,2,3,6,7], value: [5,3,4,1,8,4]}

Warning

This tendency does not accept the common start, duration, or end parameters. These are derived directly from the required time list.

Periodic Tendencies¶

These tendencies represent various oscillating waveforms (Sine, Sawtooth, Triangle, Square). They share common parameters for defining the oscillation's characteristics.

Common Periodic Parameters¶

type: The type of the oscillating waveform. Examples of each type are shown below.
frequency: The number of cycles per unit time. Defaults to 1.0 if period is also omitted.
period: The duration of one cycle.
base: The baseline or center value of the oscillation (average value).
amplitude: The amplitude of the oscillation.
min: The minimum value reached by the oscillation.
max: The maximum value reached by the oscillation.
phase: The phase shift in radians. A positive phase shifts the waveform to the left. Defaults to 0. The value is wrapped to the interval [0, 2π).
start, duration, end: See Common Time Parameters.

Warning

Providing both frequency and period is invalid if frequency != 1 / period. Providing more than two of base, amplitude, min, max is also not valid.

Sine Wave¶

A smooth oscillation following a sine function.

Type: sine

- {type: sine, base: 8, amplitude: 2, frequency: 1, duration: 4}

Sawtooth Wave¶

Linearly increases from minimum to maximum, then instantly drops back to minimum.

Type: sawtooth

- {type: sawtooth, base: 8, amplitude: 2, frequency: 1, duration: 4}

Triangle Wave¶

Linearly increases from minimum to maximum, then linearly decreases back to minimum.

Type: triangle

- {type: triangle, base: 8, amplitude: 2, frequency: 1, duration: 4}

Square Wave¶

Instantly switches between minimum and maximum values.

Type: square

- {type: square, base: 8, amplitude: 2, frequency: 1, duration: 4}

Last update: 2026-05-21