.. _auto_curve_get_x_at_deviation:

*RETURN THE X-VALUE FROM WHICH THE CURVE 2 DEVIATES FROM CURVE1*
================================================================

Compares two curves and returns the x-value at which Curve 2 first meaningfully deviates from Curve 1, using configurable y- and x-tolerance thresholds. Use this worker to detect onset points such as yield, separation, or bifurcation between a reference and a test curve.

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

Classification: **process**.

Tagged: ``curve_comparison``, ``curve_deviation``, ``deviation_detection``, ``onset_detection``, ``tolerance``, ``transformations``, ``x_at_deviation``.

Inputs
------

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

   * - Label
     - ID
     - Type
     - Default
     - Required
     - Description
   * - Curve 1
     - curve1
     - vector
     - —
     - 
     - Reference curve (Curve 1) supplied as an x-y vector; serves as the baseline against which Curve 2 is compared.
   * - Curve 2
     - curve2
     - vector
     - —
     - 
     - Test curve (Curve 2) supplied as an x-y vector; deviations from Curve 1 are measured on this curve.
   * - Y Tolerance
     - y_tol
     - scalar
     - 0.01
     - 
     - Fractional y-deviation threshold: a y-difference is flagged as deviation when it exceeds y_tol × (YMAX − YMIN); defaults to 0.01 (1 % of the y-range).
   * - X Tolerance
     - x_tol
     - scalar
     - 0.01
     - 
     - Fractional x-persistence threshold: the y-deviation must sustain over x_tol × (XMAX − XMIN) before it is declared a true deviation; defaults to 0.01 (1 % of the x-range).
   * - Y-Tolerance
     - y_tol_for_zero
     - scalar
     - 0.25
     - 
     - Proximity multiplier applied to y_tol to define how close the two curves must be before the search for deviation begins; defaults to 0.25 (i.e., the curves must agree within 25 % of y_tol).
   * - Auto-Adjust Tolerance
     - auto_adjust_tol
     - list
     - no
     - 
     - Set to 'yes' to automatically reduce the y- and x-tolerances and retry when the supplied values are larger than the data can resolve; defaults to 'no'.
   * - Number Of Auto Adjusts
     - num_auto_adjusts
     - scalar
     - 3
     - 
     - Number of times the tolerances are reduced by 50% each time
   * - Start after this X
     - x_start
     - scalar
     - 0.0
     - 
     - If the value is crossover, we find the first crossover point

Outputs
-------

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

   * - Label
     - ID
     - Type
     - Description
   * - curve_subtract_from_output
     - curve_subtract_from_output
     - scalar
     - Scalar x-value (in the same units as the input curves' x-axis) at which Curve 2 first deviates from Curve 1 according to the specified tolerances.

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

- data.curve.pair

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

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

.. raw:: html

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   <p style="font-size:11px;color:#888">
   Auto-generated from <code>transformation</code> schema. Worker id: <code>curve_get_x_at_deviation</code>. Schema hash: <code>ea8809d8e92f</code>. Hand-curated docs in <code>workerexamples/</code> override this page when present.
   </p>