SHTOOLS/SHTOOLS: Version 4.2

Change log:

• Full support added for the use of unnormalized harmonics in the classes SHCoeffs and SHGrid. To make use of this normalization, just specify normalization='unnorm'.
• Added a new python native routine mag_spectrum() in the subpackage gravmag that replaces the original fortran wrapped routines. The old python wrapped functions have been removed from pyshtools. This new routine is nearly the same as spectrum(), and further allows one to compute the spectrum of the potential or magnetic intensity.
• The old fortran based SHRead function has been replaced with a python native version shread(). The functionality is nearly identical as before, and combines the previous routines SHRead, SHReadError, SHReadErrorH and SHReadH into one. Differences include: (1) It is no longer necessary to specify the lmax of the file: This is determined automatically by reading the file from the end, (2) both real and complex coefficients are supported, (3) a header line can be output, but it is a simple list of type str that will need to be converted to the correct format by the user, and (4) "comment" lines are read and ignored: A valid line is one where there are 4 or more words, and where the first two words are integers.
• A new python native function convert() was added in the subpackage shio that converts between arrays of spherical harmonic coefficients with different normalizations. The class SHCoeffs was then simplified by using this external function for all conversions involving SHCoeffs class instances.
• The optional parameter lmax was added to SHCoeffs.spectrum().
• When plotting grids from the class SHGrid, one can now specify the label to use for the x and y axes with xlabel and ylabel, as well as the interval to use when plotting ticks on both axes using tick_interval.
• The pyshtools rotation routines now allow you to specify the optional parameter convention to treat Euler angles in either the x or y conventions (i.e., which axes to use for the second rotation). Furthermore, the optional argument body allows you to specify if you want to rotate the body (True), or coordinate system (False, default). The tutorial number 3 was updated to clear up some inconsistencies in how the angles were defined.
• New optional parameters added to SHWindow.plot_windows() and SHWindow.plot_spectra() that include xlim and ylim for the limits when plotting spectra, maxcolumns for the number of columns to use when plotting several windows, and lmax which controls the grid spacing when plotting the windows.
• Added the optional argument lmax to SHCoeffs.from_random() that allows you to create coefficients with maximum bandwidths that are either greater or less than the bandwidth of the input power spectrum.
• Added a warning message when using SHCoeffs.rotate() with degrees greater than 1200, as the routine is not accurate beyond this value.
• Added an optional argument legend to SHWindow.plot_windows() to control whether the legend is plotted or not.
• Fixed a minor bug in ClassExample.py file concerning the use of SHCoeffs.rotate().
• Added support for plotting to an already existing figure by allowing the user to specify an existing matplotlib axes.
• Removed some non-standard ascii dashes in the documentation files, and forced all doc files to be opened as utf-8.
• HTML documentation was completely redone using Jekyll. The markdown source files are now located in pages/mydoc. A static html web site is built using jekyll, whose files are located in doc. Github will automatically create the static pages and serve them on shtools.github.io/SHTOOLS. To build the static pages yourself, it is only necessary to execute bundle exec jekyll build in the directory doc, which will build the site into _site in the same directory. Alternatively, make www in the main directory will create a static site in the top-level directory www that could be used to deploy on a different web server. The site is based on the template Jekyll documentation theme by @tomjoht.