ianafast

This IDL facility provides an interface to 'anafast' F90 and 'anafast_cxx' C++ facilities. It can be used to produce the Spherical Harmonics coefficients ($a_{\ell m}$ of a HEALPix map (or pair of maps) and/or the resulting auto (or cross) power spectra $C(\ell)$.

Location in HEALPix directory tree: src/idl/interfaces/ianafast.pro 

FORMAT

IDL> IANAFAST, map1_in[, cl_out, alm1_out=, alm2_out=, binpath=, cxx=, double=, help=, healpix_data=, iter_order=, keep_tmp_files=, map2_in=, maskfile=, nested=, nlmax=, nmmax=, ordering=, plmfile=, polarisation=, regression=, ring=, show_cl=, simul_type=, silent=, theta_cut_deg=, tmpdir=, weighted=, won=, w8file=, w8dir=]

QUALIFIERS

map1_in

required input: 1st input map, can be a FITS file, or a memory array containing the map to analyze

cl_out

optional output: auto or cross power spectrum $C(\ell)$, can be a FITS file or a memory array

KEYWORDS

alm1_out=

output alm of 1st map, must be a FITS file default:alm not kept

alm2_out=

output alm of 2nd map (if any, must be a FITS file) default:alm not kept

binpath=

full path to back-end routine default:$HEXE/anafast, then $HEALPIX/bin/anafast or $HEALPIX/bin/anafast_cxx if cxx is set
– a binpath starting with / (or $\backslash$),   or $ is interpreted as absolute
– a binpath starting with ./ is interpreted as relative to current directory
– all other binpaths are relative to $HEALPIX

/cxx

if set, the C++ back-end anafast_cxx is invoked instead of F90 anafast, AND the parameter file is written accordingly

/double

if set, I/O is done in double precision default:single precision I/O

/help

if set, prints extended help

healpix_data=

same as w8dir

iter_order=

order of iteration in the analysis default:0

/keep_tmp_files

if set, temporary files are not discarded at the end of the run

map2_in=

2nd input map (FITS file or array), if provided, Cl_out will contain the cross power spectra of the 2 maps default:no 2nd map

maskfile=

pixel mask (FITS file or array) default:no mask

/nested=

if set, signals that *all* maps and mask read online are in NESTED scheme (does not apply to FITS file), see also /ring and Ordering

nlmax=

maximum multipole of analysis, *required* for C++ anafast_cxx, optional for F90 anafast

nmmax=

maximum degree m, only valid for C++ anafast_cxx default:nlmax

ordering=

either 'RING' or 'NESTED', ordering of online maps and masks, see /nested and /ring

plmfile=

FITS file containing precomputed Spherical Harmonics (deprecated) default:no file

/polarisation

if set analyze temperature + polarization (same as simul_type = 2)

regression=

0, 1 or 2, regress out best fit monopole and/or dipole before alm analysis default:0, analyze raw map

/ring

see /nested and ordering above

/show_cl

if set, and cl_out is defined, the produced $\ell(\ell+1)C(\ell)/2\pi$ will be plotted

simul_type=

1 or 2, analyze temperature only or temperature + polarization

/silent

if set, works silently

theta_cut_deg=

cut around the equatorial plane

tmpdir=

directory in which are written temporary files default:IDL_TMPDIR (see IDL documentation)

weighted=

same as won default:see won

won=

if set to 0, no weighting applied, if set to 1, a ring-based quadrature weighting scheme is applied, if set to 2, a pixel-based quadrature weighting scheme is applied. default:1: apply ring-based weighting

w8file=

In F90: FITS file containing weights default:determined automatically by back-end routine. Do not set this keyword unless you really know what you are doing
In C++ (/cxx flag): must be set to full path of weight file, consistent with value of won (or weighted)

w8dir=

In F90 only: directory where the weights are to be found default:determined automatically by back-end routine

DESCRIPTION

ianafast is an interface to 'anafast' F90 and 'anafast_cxx' C++ facilities. It requires some disk space on which to write the parameter file and the other temporary files. Most data can be provided/generated as an external FITS file, or as a memory array.

RELATED ROUTINES

This section lists the routines related to ianafast

idl

version 6.4 or more is necessary to run ianafast.

anafast

F90 facility called by ianafast.

anafast_cxx

C++ called by ianafast.

ialteralm

IDL Interface to F90 alteralm

iprocess_mask

IDL Interface to F90 process_mask

ismoothing

IDL Interface to F90 smoothing

isynfast

IDL Interface to F90 synfast

EXAMPLE:

whitenoise = randomn(seed, nside2npix(256))

ianafast, whitenoise, cl, /ring, /silent

plot, cl[*,0]

will plot the power spectrum of a white noise map