.. _auto_curve_lookup_ttz:

*COMPUTE THE INTERSECTION OF THE CURVE WITH THE Y=0 AXIS AND RETURN THE X-VALUE AS SPECIFIED BELOW. USEFUL FOR DETERMINING THE TIME-TO-ZERO VELOCITY.*
======================================================================================================================================================

Finds the x-axis value (typically time) at which a curve crosses zero on the Y-axis, commonly used to extract the time-to-zero velocity from a velocity time-history. When multiple zero-crossings exist, the lookup type controls which intersection is returned (first, last, average, min, or max x-value).

When to use
-----------

Classification: **process**.

Tagged: ``curve-lookup``, ``intersection``, ``kinematics``, ``time-to-zero``, ``ttz``, ``velocity``, ``zero-crossing``.

Inputs
------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20 20 20

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve 1
     - curve1
     - vector
     - —
     - 
     - Velocity time-history curve (X = time, Y = velocity) whose Y=0 crossing(s) will be located; accepts any curve vector but is most meaningful for velocity or similarly signed signals.
   * - Lookuptype
     - lookuptype
     - string
     - first
     - 
     - Selection strategy when multiple Y=0 crossings exist: 'first' (default) returns the earliest, 'last' the latest, 'average' the mean x-value across all crossings, 'min' the smallest x-value, and 'max' the largest x-value.

Outputs
-------

.. list-table::
   :header-rows: 1
   :widths: 20 20 20 20

   * - Label
     - ID
     - Type
     - Description
   * - curve_lookup_ttz_output_1
     - curve_lookup_ttz_output_1
     - scalar
     - Scalar x-axis value (e.g., time in ms) at which the input curve intersects Y=0, resolved according to the chosen lookup type.

Disciplines
-----------

- data.curve.transform
- engineering.crash.dynamics

Runnable example
----------------

A runnable example is registered for this worker. Open the example workflow on the d3VIEW canvas: `/api/workflow/example?id=curve_lookup_ttz <https://www.d3view.com/api/workflow/example?id=curve_lookup_ttz>`_

.. raw:: html

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   <p style="font-size:11px;color:#888">
   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_lookup_ttz</code>. Schema hash: <code>9a02d0abfabc</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>