Compute harmonic linear combinations of maps
FORTRAN
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Makefile
README
combine_main.f90
combine_modules.f90
input.cfg

README

NAME

       HLC_combine - compute harmonic linear combinations of maps


DESCRIPTION

       This program computes a harmonic linear combination (HLC) of
       the nine Planck temperature frequency maps (3 from LFI, 6 from
       HFI) with multipole-dependent weights to produce a spherical
       map. The (lmax+1)*9 harmonic weights are externally supplied
       (i.e., read from an input file) and can be determined from an
       algorithm like SMICA, for instance.

       When applied to Planck input data, the HLC output may be an
       estimated CMB map or the map of any other component, depending
       on the HLC weights. Of course, the application of the
       algorithm is not restricted to data maps; it can also be used
       to propagate noise simulations.

       The code is fully parallelized, a typical usage to compute a
       large number of simulations would be to distribute the work
       load over many nodes (using MPI), and enable OpenMP to work
       with a few cores per node on a single realization.

       It has been tested with recent versions of the Intel
       Fortran compiler using hybrid MPI and OpenMP parallelization.


INSTALLATION

       Prerequisites: - Healpix
                      - CFITSIO
                      - Modern Fortran compiler with MPI wrapper

       Prior to compilation, edit the 'Makefile' to reflect your MPI
       compiler wrapper. Also, make sure that the CFITSIO library, and
       the Healpix library and include directories are correctly
       specified.


USAGE

       The algorithm reads keyword - keyvalue pairs from a namelist in
       the configuration file 'input.cfg'. Here, the user is asked to
       specify

       FILE_IN_W8RING_DIR:
          Directory of the Healpix pixel weights, typically
          $HEALPIX/data. Only the directory should be specified, the
          file name itself will be appended according to the Healpix
          naming convention.

       FILE_IN_HLC_COEFF:
          HLC coefficients to be used to calculate the linear
          combination. It must be in ASCII table form, with 9 columns
          for the different frequencies, and lmax+1 rows.

       FILE_FILENAMELIST:
          Text file that contains the list of input and output file
          names, one entry per line. The file names must be provided
          in the following order:

	  Input file simulation 1 LFI  30 GHz
	  Input file simulation 1 LFI  44 GHz
	  Input file simulation 1 LFI  70 GHz
	  Input file simulation 1 HFI 100 GHz
	  Input file simulation 1 HFI 143 GHz
	  Input file simulation 1 HFI 217 GHz
	  Input file simulation 1 HFI 353 GHz
	  Input file simulation 1 HFI 545 GHz
	  Input file simulation 1 HFI 857 GHz
	  Output file simulation 1
	  Input file simulation 2 LFI  30 GHz
	  Input file simulation 2 LFI  44 GHz
	  Input file simulation 2 LFI  70 GHz
	  Input file simulation 2 HFI 100 GHz
	  Input file simulation 2 HFI 143 GHz
	  Input file simulation 2 HFI 217 GHz
	  Input file simulation 2 HFI 353 GHz
	  Input file simulation 2 HFI 545 GHz
	  Input file simulation 2 HFI 857 GHz
	  Output file simulation 2
	  ...

	  This text file must not contain comments, blank lines,
	  whitespaces, etc.

	  The format to specify the output file names follows the
	  Healpix convention. That is, if it is prepended with an
	  exclamation point, "!", possibly existing output files will
	  be overwritten.

	  The total number of simulations that can be supplied in the
	  file and subsequently processed in a single run of the
	  pipeline is currently limited to 10000. File names should
	  contain absolute paths and be at most 150 characters long.


RESTRICTIONS

       The software package HLC_combine does not implement a universal
       HLC. In its latest version, it is restricted to the Planck
       format in the sense that it assumes a total of nine input maps,
       the first three of which are provided at resolution nside=1024,
       and the last six at nside=2048.

       Input files are expected to be in the Healpix ordering scheme
       'RING'. If maps are provided in 'NESTED' format, and a valid
       FITS header containing the "ORDERING='NESTED'" entry is
       present, the input will be automatically reordered into 'RING'
       scheme. Irrespective of the input, the output map will always
       be stored in single precision and 'RING' ordering.

       One MPI instance of the program demands about 4 GB of
       memory. Make sure that your computing environment complies with
       this requirement.