This IDL routine provides a means to convert the a_lm 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

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).

idl: version 6.1 or more is necessary to run lm2index.
fits2alm: reads a FITS file containing a_lm values.
alm2fits: writes a_lm values into a FITS file.
index2lm: routine complementary to lm2index: converts i = l² + l + m + 1 into (l, m).

lm2index, l, m, index

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

Eric Hivon 2010-06-18

Contact:

Site Manager:
Webmaster:
CL 03-2650