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sph_tools - a helper module for spherical harmonic transformation

sph_tools - a helper module for spherical harmonic transformation#

Routines for generalized map2alm and alm2map (healpix and CAR).

pspy.sph_tools.alm2map(alms, template)#

alm2map transform (for healpix and CAR).

Parameters:

  • alms (array) – a set of alms, the shape of alms should correspond to so_map.ncomp

  • template (so_map) – the map template

pspy.sph_tools.get_alms(so_map, window, niter, lmax, theta_range=None, dtype=<class 'numpy.complex128'>)#

Get a map, multiply by a window and return alms This is basically map2alm but with application of the window functions.

Parameters:

  • so_map (so_map) – the data we wants alms from

  • window (so_map or tuple of so_map) – a so map with the window function, if the so map has 3 components (for spin0 and 2 fields) expect a tuple (window,window_pol)

  • range (theta) – for healpix pixellisation you can specify a range [theta_min,theta_max] in radian. All pixel outside this range will be assumed to be zero.

pspy.sph_tools.get_pure_alms(so_map, window, niter, lmax)#

Compute pure alms from maps and window function

Parameters:

  • so_map (so_map) – the data we wants alms from

  • window (so_map or tuple of so_map) – a so map with the window function, if the so map has 3 components (for spin0 and 2 fields) expect a tuple (window,window_pol)

  • niter (integer) – the number of iteration performed while computing the alm not that for CAR niter=0 should be enough

  • lmax (integer) – the maximum multipole of the transform

pspy.sph_tools.map2alm(map, niter, lmax, theta_range=None, dtype=<class 'numpy.complex128'>)#

Map2alm transform (for healpix or CAR).

Parameters:

  • map (so_map) – the map from which to compute the alm

  • niter (integer) – the number of iteration performed while computing the alm not that for CAR niter=0 should be enough

  • lmax (integer) – the maximum multipole of the transform

  • theta_range (list of 2 elements) – [theta_min,theta_max] in radian. for healpix pixellisation all pixel outside this range will be assumed to be zero.

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