.. _auto_curve_lookup_xvalueat:

* COMPUTE THE VALUE OF X FOR A GIVEN Y VALUE*
=============================================

Given a 2-D curve and a target Y value, performs an inverse lookup to return the corresponding X value. Use this worker whenever you need to invert a curve relationship, e.g. finding the time at which a signal crosses a threshold.

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

Classification: **process**.

Tagged: ``curve``, ``interpolation``, ``inverse``, ``lookup``, ``threshold``, ``x-value``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve 1
     - curve1
     - vector
     - —
     - 
     - The source 2-D curve (X/Y vector pairs) from which the inverse lookup will be performed; must contain the target Y value within its range.
   * - Y Value
     - y_value
     - float
     - —
     - 
     - The Y value (float) at which the corresponding X value is to be found; must lie within the Y range of the supplied curve.
   * - Format
     - format
     - string
     - %s
     - 
     - Printf-style format string controlling how the resulting X value is rendered (e.g. '%.4f' for four decimal places); defaults to '%s' (pass-through string representation).

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curve_lookup_xvalueat_output_1
     - curve_lookup_xvalueat_output_1
     - scalar
     - Scalar X value interpolated from the curve at the specified Y value, formatted according to the 'format' input.

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

- data.curve.transform

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

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

.. raw:: html

   <hr style="margin-top:2em">
   <p style="font-size:11px;color:#888">
   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_lookup_xvalueat</code>. Schema hash: <code>86ca03e44067</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>