# Copyright (c) 2018 The Harmonica Developers.
# Distributed under the terms of the BSD 3-Clause License.
# SPDX-License-Identifier: BSD-3-Clause
#
# This code is part of the Fatiando a Terra project (https://www.fatiando.org)
#
"""
Apply transformations to regular grids of potential fields
"""
from .filters import derivative_upward_kernel
from .filters._utils import apply_filter
[docs]def derivative_upward(grid, order=1):
"""
Calculate the derivative of a potential field grid in the upward direction
Compute the spatial derivative in the upward direction of regular gridded
data using frequency domain calculations through Fast Fourier Transform.
Parameters
----------
grid : :class:`xarray.DataArray`
A two dimensional :class:`xarray.DataArray` whose coordinates are
evenly spaced (regular grid). Its dimensions should be in the following
order: *northing*, *easting*. Its coordinates should be defined in the
same units.
order : int
The order of the derivative. Default to 1.
Returns
-------
derivative : :class:`xarray.DataArray`
A :class:`xarray.DataArray` with the upward derivatives of the passed
``grid``. Its units are the same units of the ``grid`` per units of its
coordinates.
References
----------
[Blakely1995]_
See also
--------
harmonica.filters.derivative_upward_kernel
"""
return apply_filter(grid, derivative_upward_kernel, order=order)
