Installing and using the IDL interfaces

The Healpix package provides all the routines to read, write and manipulate Healpix maps in IDL. S2LET completes this framework by providing similar routines for the MW sampling. Interfaces for the spherical harmonic and the wavelet transforms are provided for both samplings and allow for the same flexibility as in the C and Matlab code. In particular, S2LET enables to work either with MW of Healpix maps from the FITS files to the output wavelets plotted in Mollweide projection.

To use the IDL interfaces, one must first build the dynamic C library according to the instructions of this page (i.e. by running make dylib). The variable S2LET must be defined in Bash/Shell and point to the root of the S2LET directory so that IDL can find the dynamic library. Note that CFITSIO and HEALPIX are required to support for the Healpix spherical harmonic transform as well as the FITS input-output routines.


Source code documentation

The IDL code is extensively documented and multiple examples are provided to illustrate its use. The documentation for the individual functions can either be found in the code or through the DOC_LIBRARY command in IDL itself. Alternatively, the HTML version of this documentation is available here.


Testing and using the interfaces

Once the dynamic library is built, you may add s2let/main/src/idl in the IDL path in order to run the IDL functions from elsewhere.

Functions

A list of the high-level IDL functions, with brief descriptions is given here:

  s2let_axisym_mw_wav_analysis
  Compute exact wavelet transform of a MW signal sampled on the sphere

  s2let_axisym_mw_wav_synthesis
  Exactly reconstuct a MW signal on the sphere from its wavelets

  s2let_mw_read_real_map
  Read a MW map from a FITS file

  s2let_mw_write_real_map
  Write a MW map to a FITS file

  s2let_hpx_alm2map_real
  Interface to the Fortran function alm2map in Healpix
  (ring ordered, inverse spherical harmonic transform)

  s2let_hpx_map2alm_real
  Interface to the Fortran function map2alm in Healpix
  (ring ordered, forward spherical harmonic transform)

  s2let_axisym_hpx_wav_analysis
  Compute wavelet transform of a Healpix map (ring ordered)

  s2let_axisym_hpx_wav_synthesis
  Reconstuct a Healpix map (ring ordered) on the sphere from its wavelets

  s2let_mw_plot_mollweide
  Plot an MW map using Mollweide projection  

To access the documentation for each function in IDL, simply run:

 >> DOC_LIBRARY, "<function>"

where <function> is the function name.

Demos

A number of demos are provided to illustrate the use of the idl interface.

  s2let_test
  Run and test all functionalties of the wavelet transform (MW sampling)

  s2let_demo1
  Compute and plot wavelets of Earth tomography data
  (full and multi-resolution, MW sampling)

  s2let_demo2
  Compute and plot wavelets of a random CMB simulation
  (Healpix sampling converted into MW)

  s2let_hpx_demo
  Compute and plot wavelets of a random CMB simulation (Healpix sampling)