pastas.stressmodels.WellModel.variance_gain
===========================================

.. py:method:: pastas.stressmodels.WellModel.variance_gain(model: pastas.typing.Model, istress: int | None = None, r: pastas.typing.ArrayLike | None = None) -> float

   
   Calculate variance of the gain for WellModel.

   Variance of the gain is calculated based on propagation of uncertainty using
   optimal parameter values and the estimated variances of A and b and the
   covariance between A and b.

   :param model: optimized model
   :type model: pastas.Model
   :param istress: index of stress(es) for which to calculate variance of gain
   :type istress: int or list of int, optional
   :param r: radial distance(s) at which to calculate variance of the gain,
             only considered if istress is None
   :type r: array_like, optional

   :returns: **var_gain** -- variance of the gain calculated from model results for parameters A and b.
   :rtype: float

   .. seealso:: :py:obj:`pastas.HantushWellModel.variance_gain`















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