.. _weightsFile:

Weights file
============

This file supplies the user-based weights that acts upon the model objective function. Each set of weights correspond to the functions (e.g., :math:`w_x`) given in the :ref:`model objective function <mof>`. For ease, the weights in geographic coordinates are provided by the user. The following is the file structure is for the weights file:


.. figure:: ../../images/weightsInp.png
    :align: center
    :figwidth: 50%


Parameter definitions:

- W.S\ :math:`_{i,j,k}`: Cell weights for the smallest model component in the :ref:`model objective function <mof>`.

- W.E\ :math:`_{i,j,k}`: Cell weights for the interface perpendicular to the easting direction.

- W.N\ :math:`_{i,j,k}`: Cell weights for the interface perpendicular to the northing direction.

- W.S\ :math:`_{i,j,k}`: Cell weights for the interface perpendicular to the vertical direction.

Within each part, the values are ordered in the same way as in :ref:`model file <modelFile>`, however, they can be all on one line, or broken up over several lines. Since the weights for a derivative term are applied to the boundary between cells, the weights have one fewer value in that direction. For instance, the weights for the derivative in easting direction has :math:`(NE-1) \times NN \times NZ` values, whereas the number of cells is :math:`NE \times NN \times NZ`.

If the surface is supplied, the cell weights above the surface will be ignored. It is recommended that these weights be assigned a value of ``-1.0`` to avoid confusion. If ``null`` is entered instead of the weights file, then all of the cell weights will be set equal (``1.0``).