************************************************************************************************
    C++ code for computing the window function factor for going from angular power spectra 
    C_l to expected variance \sigma^2 (of the real space variable) inside the window function
    w(\theta):

    \sigma^2 = \sum_l ( \sum_m |w_{lm}|^2 ) C_l
                      ^^^^^^^^^^^^^^^^^^^^^
		      window function factor    
************************************************************************************************


USAGE: 
windowL <Healpix map FITS file> <ASCII output file> <Map effective area file (optional)>

OUTPUT:
 - ASCII file containing two columns: l and the window function factor.
 - If an extra parameter is provided as input (<Map effective area file>), 
   the code outputs to this file the map effective area (sum of the pixel values normalized 
   to pixel area, this makes sense if 0<pixel values<1) in square degrees.

COMPILING:
 - This code depends on: Healpix libraries and data, FITSIO library. OpenMP would be nice.
 - Edit the Makefile to change some variables like compiler and Healpix directory. You 
   might need to change the Healpix cxx flavour as well (basic or generic) and possibly 
   the location of the cfitsio library.
 - On your terminal, in the code's directory, run: make

ATTENTION:
 - The code is hard-wired to set every pixel to either 0 or 1 depending if its value 
   is <1 or >1. This can be changed in windowL.cpp (#define BINARIZE). 


Written by Henrique S. Xavier on 13/08/2015 at UCL, London
Contact: hsxavier@if.usp.br