alm2map_spin*
This routine produces the maps of arbitrary spin and given their alm
coefficients.
A (complex) map of spin is a linear combination of the spin weighted harmonics
|
(3) |
for
,
and is such that
.
The
usual phase convention for the spin weighted harmonics
is
and therefore
.
alm2map_spin* expects the alm coefficients to be provided as
for , knowing that, just as for spin 0 maps, the
coefficients for are given by
The two (real) maps produced by alm2map_spin* are defined respectively as
With these definitions, , , and
match HEALPix polarization
and respectively. However, for
,
,
,
,
When dealing only with scalar quantities, like temperature or intensity maps, having a spin , it is
highly recommended, and much more memory-efficient, to use directly the routine alm2map, rather then setting spin in alm2map_spin*.
Location in HEALPix directory tree: src/f90/mod/alm_tools.F90
FORMAT
ARGUMENTS
name & dimensionality |
kind |
in/out |
description |
|
|
|
|
nsmax |
I4B |
IN |
the
value of the map to synthesize. |
nlmax |
I4B |
IN |
the maximum value used for the
. |
nmmax |
I4B |
IN |
the maximum value used for the
. |
spin |
I4B |
IN |
spin of the maps to be generated (only its absolute value
is relevant). |
alm(1:2, 0:nlmax, 0:nmmax) |
SPC/ DPC |
IN |
The
and
values to make the map
from. |
map(0:12*nsmax**2-1, 1:2) |
SP/ DP |
OUT |
and
output maps |
zbounds(1:2), OPTIONAL |
DP |
IN |
section of the sphere on which to perform the map synthesis, expressed in terms of
If zbounds(1)zbounds(2), it is
performed on the strip zbounds(1)zbounds(2); if not,
it is performed outside the strip
zbounds(2)zbounds(1). If absent, the whole map is processed.
|
EXAMPLE:
use healpix_types
use pix_tools, only : nside2npix
use alm_tools, only : alm2map_spin
integer(I4B) :: nside, lmax, mmax, npix, spin
real(SP), dimension(:,:), allocatable :: map
complex(SPC), dimension(:,:,:), allocatable :: alm
...
nside=256 ; lmax=512 ; mmax=lmax ; spin=4
npix=nside2npix(nside)
allocate(alm(1:2,0:lmax,0:mmax))
allocate(map(0:npix-1,1:2))
...
call alm2map_spin(nside, lmax, mmax, spin, alm, map)
Make spin-4 maps from the
passed in alm. The maps have
of 256, and are constructed from
values up to 512 in and .
MODULES & ROUTINES
This section lists the modules and routines used by alm2map_spin*.
-
ring_synthesis
- Performs FFT over for synthesis of the rings.
-
compute_lam_mm, get_pixel_layout,
-
gen_lamfac_der, gen_mfac, gen_mfac_spin, do_lam_lm_spin,
-
gen_recfac, gen_recfac_spin, init_rescale, l_min_ylm
- Ancillary routines used
for
recursion
-
misc_utils
- module, containing:
-
assert_alloc
- routine to print error message, when an array can not be
allocated properly
Note: Starting with version 3.80, some libsharp routines will be called for any value.
RELATED ROUTINES
This section lists the routines related to alm2map_spin*
-
alm2map
- routine generating maps of temperature
and polarisation from their
-
alm2map_der
- routine generating maps of temperature
and polarisation, and their spatial derivatives, from their
-
map2alm_spin
- routine performing the inverse transform
of alm2map.
-
create_alm
- routine to generate randomly
distributed
coefficients according to a given power spectrum
Version 3.83, 2024-11-13