lm2index


This IDL routine provides a means to convert the alm degree and order (l, m) into the index i=l2 + l+ m + 1 (in order to be fed to alm2fits routine for instance)

Location in HEALPix directory tree: ">src/idl/misc/lm2index.pro

 


FORMAT

IDL> LM2INDEX, l, m, index


QUALIFIERS

l
Long array containing on INPUT the order l.
m
Long array containing on INPUT the degree m.
index
Long array containing on OUTPUT the index
i = l2 + l + m + 1.


DESCRIPTION

lm2index converts (l, m) into i=l2 + l+ m + 1. Note that by definition $0 \le \vert m\vert\le l$ (the routine does not check for this).


RELATED ROUTINES

This section lists the routines related to lm2index

idl
version 6.4 or more is necessary to run lm2index.
fits2alm
reads a FITS file containing alm values.
alm2fits
writes alm values into a FITS file.
index2lm
routine complementary to lm2index: converts i = l2 + l + m + 1 into (l, m).


EXAMPLE:

lm2index, l, m, index
will return in index in value l2 + l+ m + 1

Version 3.31, 2017-01-06