A class for the horizontal components of the gradient of a scalar function.

## Initialization

Initialization method Description
x = SHCoeffs.gradient() Initialize using an SHCoeffs class instance.

## Class attributes

Attribute Description
theta SHGrid class instance of the theta component of the horizontal gradient.
phi SHGrid class instance of the phi component of the horizontal gradient.
lmax The maximum spherical harmonic degree resolvable by the grids.
lmax_calc The maximum spherical harmonic degree used in creating the grids.
units The units of the gridded gradients.
nlat, nlon The number of latitude and longitude bands in the grids.
sampling The longitudinal sampling scheme of the grids: either 1 for nlon = nlat or 2 for nlon = 2 * nlat.

## Class methods

Method Description
plot() Plot the two components of the horizontal gradient.
plot_theta() Plot the theta component of the horizontal gradient.
plot_phi() Plot the phi component of the horizontal gradient.
to_xarray() Return the gridded gradient data as an xarray DataSet.
copy() Return a copy of the class instance.
info() Print a summary of the data stored in the SHGradient instance.