alm_t2i


This IDL facility turns a tabular (real or complex) a(l,m) array into an indexed list of alm that can be written into a FITS file with alm2fits

Location in HEALPix directory tree: src/idl/misc/alm_t2i.pro 


FORMAT

IDL> alm_t2i, Alm_table, Index, Alm_vec, [/HELP, /MFIRST])


QUALIFIERS

Alm_table
Input real or complex array, containing all the aslm for l in [0,$l_{\rm max}$] and m in [0,$m_{\rm max}$] (and s in [0,$s_{\rm max}$] if applicable)
if REAL it has 3 (or 4) dimensions,
if COMPLEX is has 2 (or 3) dimensions

Index
Output integer vector of size ni containing the index i of the of alm coefficients, related to {l,m} by i = l2 + l + m + 1
Alm_vec
Output array of alm coefficients, with dimension (ni, 2 [,$s_{\rm max}+1$]) where
ni = number of i indices
2 for real and imaginary parts of alm coefficients
$s_{\rm max}+1$ = number of signals (usually 1 for any of T E B or 3 for T,E,B together)


KEYWORDS

/HELP
if set, prints out the help header and exits
/MFIRST
if set, the input array is a(m,l) instead of a(l,m)


DESCRIPTION

alm_t2i turns a real or complex tabular array of a(l,m) (or a(m,l) is MFIRST is set) into a real list of alm (with the real and imaginary parts separated) and its index i=l2+l+m+1. The unphysical m>l elements of the input table are dropped from the output list.


RELATED ROUTINES

This section lists the routines related to alm_t2i

idl
version 6.4 or more is necessary to run alm_t2i.
alm_i2t
this function is complementary to alm_t2i and turns an indexed list of alm (as generated by fits2alm) into a tabular (real or complex) a(l,m) array for easier manipulation
alm2fits, fits2alm
routines to read and write alm indexed lists from and to FITS files.


EXAMPLE:

See alm_i2t example

Version 3.31, 2017-01-06