This ends with an error

~/SphericalHarmonics/shtools/pyshtools/backends/ducc0_wrapper.py in _analyze_DH(map, lmax)
    175
    176 def _analyze_DH(map, lmax):
--> 177     alm = ducc0.sht.experimental.analysis_2d(
    178         map=map.reshape((1, map.shape[0], map.shape[1])),
    179         spin=0,

RuntimeError:
./python/sht_pymod.cc: 544 (py::array ducc0::detail_pymodule_sht::Py_analysis_2d(const py::array &, size_t, size_t, const std::__1::string &, py::object &, size_t, py::object &)):

type matching failed: 'alm' has neither type 'c8' nor 'c16'

clm3 = pysh.SHGravCoeffs.from_array(coeffs = np.array([C_T,S_T]), gm = GM, r0 = a)
grav = clm3.expand() < ----- here!
fig2, ax2 = grav.plot(show=False)

There are several options to control how the gravity grids are created and displayed. For example:

grav = clm3.expand(flattening = 0., normal_gravity=False)
grav.plot_pot()

I would just take a look at the documentation for the expand routine to see all the options that are available.

mreineck (mreineck): I have two quick comments about the ducc backend. The first is that I tried to select the 'ducc' backend when it wasn't install, which raised an error and exited:

ImportError: "ducc" backend requested, but not installed.

Hi everyone! This is just to let you know that we are aiming for a new release on April 18. If you want to test anything, please just pull the latest from the develop branch, and then manually install using pip install -v -e .
Here are the preliminary release notes

## Version 4.10

**Enhancements**

* Change the preferred backend from 'shtools' to 'ducc'.
* Improve handing of switching backends. Changing backends will dynamically link the correct routine to the top level modules found in `pyshtools.expand` and `pyshools.rotate`.
* Update python examples so that they don't call routines directly in the shtools backend. [See deprecation note below.]
* Add historical lunar topography dataset GLTM-2B.
* Add historical martian magnetic field models FSU50 and FSU90.
* Add new Mars gravity model MRO120F as well as several historical Mars gravity models.
* Add historical Venus topography datasets SHTJV360A01 and SHTJV360A02.
* Add Thebault2021 Earth magnetic field dataset.
* Update urls for databases hosted at GSFC.
* Reorder optional arguments in docs for `makegravgradgriddh` and `makemaggravgradgrid` for consistency with code.
* Allow 'shtools' and 'dov' file formats to contain floats for degree and order.
* Minor changes and enhancements to the documentation.

**Bug fixes**

* Fix typo regarding `nthreads` in `SHMagCoeffs.rotate()` method.
* Fix bug with `SHGravCoeffs.admittance()` when using `function='geoid'`.
* Fix bug in python wrapper of the routine `MakeGrid2D` concerning the mandatory variable `interval`.
* Add workaround to use pygmt with shading for versions >=0.4.
* Convert all grids to `float` before using the `ducc` backend.
* `SHGeoid.to_netcdf()` now outputs double precision by default (consistent with the other grid classes).
* Fix bug with `SHWindow.multitaper_cross_spectrum()` when using arbitrary localization regions.
* Fix bug with the c-wrapper for `cMakeGradientDH` regarding the optional `radius` parameter.
* Minor changes to remove deprecation warnings.

**Note:** The module `pyshtools.shtools` will be deprecated in the v4.11 release. This module represents 1 of 2 possible backends for pyshtools, and will henceforth be located at `pyshtools.backends.shtools`. Unless explicitly required, the user should avoid using the `backends` modules directly, and should instead call the routines that are located in the top level modules such as `pyshtools.expand`. Setting the backend by use of the routine `pyshtools.backends.selected_preferred_backend()` determines which backed to use when calling the routines in the top level modules.

There are three small issues that we are still trying to fix

1. the ducc backend doesn't have a conda package that works with new M1 macs (osx-arm64)
2. the pypandoc package (which isn't needed unless you are a developer) also doesn't have a conda package for osx-arm64
3. the latest version of setuptools 62.1.0 has a major bug that won't allow you to install pyshtools (v62.0.0 and lower works fine)

We are (as usual) having problems getting the wheels to build for windows. If you have any knowledge about windows, please check out this issue and help us out:

https://github.com/SHTOOLS/SHTOOLS/issues/352
https://ci.appveyor.com/project/MarkWieczorek/build-shtools