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Lissajous Curve Generator

Generate Lissajous figures by adjusting frequency ratios, phase differences, and damping. Animate the drawing process.

Tested tool guide Tested browser tools Checked August 16, 2026

What Lissajous Curve Generator does, with a checked example

A Lissajous figure is the path formed when one sinusoidal motion supplies the horizontal coordinate and another supplies the vertical coordinate. This generator lets you vary their frequency ratio, shift their relative phase, add damping, and animate the order in which the path is drawn. The common surprise is that the frequency numbers do not uniquely determine the completed undamped shape. Ratios 2:3 and 4:6 reduce to the same ratio, so over a complete repeat they trace the same locus, although their traversal timing can differ.

Worked example

A concrete input and expected output from the current implementation.

Input

frequency ratio 1:1; phase difference 0 degrees; damping 0

Expected output

A straight line segment through the center, traced back and forth without contracting.

With equal frequencies and zero phase difference, the normalized coordinates have the same sine value at every parameter time: x(t) = sin(t) and y(t) = sin(t), so y = x. Zero damping keeps the amplitude constant.

How the result is produced

1

Parametric trace

For interpreting an undamped plot, write the coordinates as x(t) = A sin(a t + delta) and y(t) = B sin(b t). The values a and b set the frequency ratio, while delta offsets one oscillation in phase. If a:b is rational, the two motions regain the same relative state after a common period and the full trace closes.

2

Damping and animation

Positive damping makes the oscillation amplitude decrease as parameter time advances. Consequently, a cycle drawn later is smaller than an earlier cycle, and repeated lobes no longer lie exactly on top of one another. The animation reveals which portion is earlier and which contracts later, information that is ambiguous in a finished still image.

Good uses

  • Checking how a 2:3 frequency relationship changes as phase is adjusted before reproducing the figure on an oscilloscope.
  • Teaching why equal-frequency, in-phase perpendicular oscillations collapse to a line while a quarter-cycle offset creates a rounded closed path.
  • Designing a damped animation that shows the drawing order of inward-contracting loops instead of only their final outline.

Limits and checks

  • The geometry does not reveal absolute frequencies. With matching phase and amplitudes, 2 Hz and 3 Hz have the same complete undamped locus as 200 Hz and 300 Hz because both pairs have ratio 2:3.
  • Phase is periodic, so 0 degrees and 360 degrees describe the same offset. Visual tilt can also depend on which oscillation receives the offset and how the vertical axis is oriented.
  • A rational frequency ratio guarantees closure only for the undamped mathematical path. Positive damping changes the amplitude between cycles, so an inward trace does not return exactly to its earlier points.

Common questions

Does a closed Lissajous figure mean the two frequencies are equal?

No. With damping set to zero, a Lissajous trace closes whenever the frequency ratio is rational, such as 2:3, because both oscillations return to their starting relationship after a common period. Equal frequencies are only the 1:1 special case. A short animation can stop before closure, so an apparently open path does not disprove eventual closure.

Why can a 1:1 ratio produce a line, an ellipse, or a circle?

Phase sets the relative starting point of the two oscillations. At 1:1, zero phase makes their normalized coordinates equal at every instant, producing a line. A quarter-cycle offset puts them in quadrature; with equal amplitudes and equal axis scales, the mathematical locus is a circle. Other nondegenerate offsets produce ellipses. Positive damping prevents later cycles from exactly retracing that locus.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.

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