S2FIL

"The S2FIL library contains functionality to support optimal filtering on the sphere. Optimal directional matched filters (MF) and scale adaptive filters (SAF) may be constructed from a template and stochastic background process. Functionality is incorporated also to filter a sky data map using an optimal filter and to detect compact objects using a naive thresholding strategy. The derivation of the optimal filters on the sphere implemented here is presented in our paper:

J. D. McEwen, M. P. Hobson, and A. N. Lasenby. Optimal filters on the sphere. IEEE Trans. Sig. Proc., in press, 2006.

The library design is based on object-oriented principles and is implemented in Fortran 90. Generally one must instantiate a class object using the corresponding init routines. The instatiated object should be freed once it is no longer required with the corresponding free routine (this deallocates all memory associated with the object).

For further details see the README.txt file.

The utility programs are:

s2fil_filter_construct: Compute optimal filter from template and background process.
s2fil_field_construct: Construct filtered field from optimal filter and data sky.
s2fil_localisation_thres: Find localised regions in filtered field using thresholding strategy. Locations and values found are written to the standard output.
s2fil_draw_dots: Draw dots on sky map at specified positions.
s2fil_draw_dots_only: Draw dots at specified positions on constant value map.

The library classes are:


s2fil_field_mod: Functionality to compute and store the coefficients of a filtered field from the optimal filter and data sky map. Interfaces with the CSWT library to actually compute the `wavelet' coefficients.
s2fil_filter_mod: Functionality to compute (and store) optimal filters from a background noise process and template function defined on the sky. Both spherical directional matched filters and scale adaptive filters may be constructed. Filters at various scales may be constrcuted either by dilating the original template (`correct' approach) or by dilating the first computed optimal filter.
s2fil_types_mod: Definition of intrinsic types and constants used in the s2fil library.
s2fil_error_mod: Functionality to handle errors that may occur in the S2FIL library. Public S2FIL error codes are defined, with corresponding private error comments and default halt execution status."

https://astro-informatics.github.io/s2fil/

http://www.jasonmcewen.org/codes.html