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 $a^s_{\ell m}$ for $\ell$ in [0, $\ell_{\mathrm{max}}$] and m in [0, m_max] (and s in [0, s_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 $a_{\ell m}$ coefficients, related to $\{\ell,m\}$ by $i = \ell^2 + \ell + m + 1$

Alm_vec

Output array of $a_{\ell m}$ coefficients, with dimension (ni, 2 [, s_max+1]) where
ni = number of i indices
2 for real and imaginary parts of alm coefficients
s_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) if MFIRST is set) into a real list of $a_{\ell m}$ (with the real and imaginary parts separated) and its index $i = \ell^2 + \ell + m + 1$. The unphysical $m>\ell$ 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 $a_{\ell m}$ indexed lists from and to FITS files.

EXAMPLE:

See alm_i2t example