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map2alm_iterative*

This routine covers and extends the functionalities of map2alm: it analyzes a (polarised) HEALPix RING ordered map and returns its a_lm coefficients for temperature (and polarisation) up to a specified multipole, and use precomputed harmonics if those are provided, but it also can also perform an iterative (Jacobi) determination of the a_lm, and apply a pixel mask if one is provided.

FORMAT

call map2alm_iterative*( nsmax, nlmax, nmmax, iter_order, map_TQU, alm_TGC [, zbounds, w8ring_TQU , plm, mask] )

ARGUMENTS

name & dimensionality	kind	in/out	description
nsmax	I4B	IN	the Nside value of the map to analyse.
nlmax	I4B	IN	the maximum l value for the analysis.
nmmax	I4B	IN	the maximum m value for the analysis.
iter_order	I4B	IN	the order of Jacobi iteration. Increasing that order improves the accuracy of the final alm but increases the computation time iter_order. iter_order =0 is a straight analysis, while iter_order =3 is usually a good compromise.
map_TQU(0:12*nsmax**2-1, 1:p)	SP/ DP	INOUT	input map. p is 1 or 3 depending if temperature (T) only or temperature and polarisation (T, Q, U) are to be analysed. It will be altered on output if a mask is provided.

alm_TGC(1:p, 0:nlmax, 0:nmmax)	SPC/ DPC	OUT	The alm values output from the analysis. p is 1 or 3 depending on whether polarisation is included or not. In the former case, the first index is (1,2,3) corresponding to (T,E,B).
zbounds(1:2), OPTIONAL	DP	IN	section of the map on which to perform the alm analysis, expressed in terms of If zbounds(1)<zbounds(2), the analysis is performed on the strip zbounds(1)<z<zbounds(2); if not, it is performed outside of the strip zbounds(2)<z<zbounds(1). If absent, the whole map is analyzed
w8ring_TQU(1:2*nsmax,1:p), OPTIONAL	DP	IN	ring weights for quadrature corrections. p is 1 for a temperature analysis and 3 for (T,Q,U). If absent, the ring weights are all set to 1.
plm(0:,1:p), OPTIONAL	DP	IN	If this optional matrix is passed, precomputed scalar (and tensor) are used instead of recursion.
mask(0:12*nsmax**2-1,1:q), OPTIONAL	SP/ DP	IN	pixel mask, assumed to have the same resolution (and RING ordering) as the map. The map map_TQU is multiplied by that mask before being analyzed, and will therefore be altered on output. q should be in {1,2,3}. If p=q=3, then each of the 3 masks is applied to the respective map. If p=3 and q=2, the first mask is applied to the first map, and the second mask to the second (Q) and third (U) map. If p=3 and q=1, the same mask is applied to the 3 maps. Note: the output alm are computed directly on the masked map, and are not corrected for the loss of power, correlation or leakage created by the mask.

EXAMPLE:

Analyses temperature and polarisation signals in the first 10000 pixels of map (as determined by mask). The map has an N_side of 256, and the analysis is supposed to be performed up to 512 in l and m. The resulting a_lm coefficients for temperature and polarisation are returned in alm. Uniform weights are assumed. In order to improve the allm accuracy, 2 Jacobi iterations are performed.

MODULES & ROUTINES

This section lists the modules and routines used by map2alm_iterative*.

ring_analysis

Performs FFT for the ring analysis.

map2alm

Perform the alm analysis

misc_util

module, containing:

assert_alloc

routine to print error message when an array is not properly allocated

RELATED ROUTINES

This section lists the routines related to map2alm_iterative*

anafast

executable using map2alm_iterative* to analyse maps.

alm2map

routine performing the inverse transform of map2alm_iterative*.

alm2map_spin

synthesize spin weighted maps.

map2alm_spin

analyze spin weighted maps.

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