DETECT SIGN CHANGES BASED ON 3RD DERIVATIVE SIGN CHANGE¶
Detects sign changes in a curve by computing its Nth-order derivative and flagging points where the derivative exceeds a ratio-based threshold. Use this worker to identify inflection points, oscillations, or instabilities in time-history or spatial curves via higher-order derivative analysis.
When to use¶
Classification: process.
Tagged: curve_analysis, derivative, higher_order, inflection_point, sign_change, threshold.
Inputs¶
| Label | ID | Type | Default | Required | Description |
|---|---|---|---|---|---|
| Curve | curve | vector | — | One or more input curves (x-y vector pairs) to analyse; accepts multiple curves — leave empty only if curves are provided downstream via a connected node. | |
| Order | order | scalar | 3 | Derivative order to compute before applying the threshold check (dimensionless integer, default 3 for the 3rd derivative); increase to detect higher-order sign changes, decrease for smoother sensitivity. | |
| Ratio | ratio | scalar | 0.75 | Fraction of the peak derivative magnitude used as the detection threshold (dimensionless, default 0.75); points whose derivative exceeds ratio × peak are flagged — lower values flag more points, higher values flag only sharp changes. |
Outputs¶
| Label | ID | Type | Description |
|---|---|---|---|
| curves_derivative_exceeds_threshold_output_1 | curves_derivative_exceeds_threshold_output_1 | vector | Output curve(s) containing the flagged points or annotated signal where the Nth-order derivative exceeds the ratio threshold, returned as an x-y vector in the same domain as the input. |
Disciplines¶
- data.curve.transform
- data.signal_processing
Runnable example¶
A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: /api/workflow/example?id=curves_derivative_exceeds_threshold
Auto-generated from transformation schema. Worker id: curves_derivative_exceeds_threshold. Schema hash: 1d24ae22f3b7. Hand-curated docs in workerexamples/ override this page when present.