This IDL routine provides a means to
read from a FITS file binary table extension(s) containing spherical
harmonic coefficients alm (and optional errors) and their index. Reads
header information if required. The facility is intended to enable
the user to read the output from the HEALPix facilities anafast and synfast.
Location in HEALPix directory tree: ">src/idl/fits/fits2alm.pro
- Long array containing the index for the corresponding
array of alm coefficients (and errors if required). The
index i is related to (l,m) by the relation
i = l2 + l + m + 1.
This has dimension
nl (see below).
- Real or double array of alm coefficients read from the
file. This has dimension (nl,nalm,nsig) - corresponding to
nl = number of (l,m) indices
nalm = 2 for real and imaginary parts of alm coefficients or
4 for above plus corresponding error values
nsig = number of signals to be written (1 for any of T E B
or 3 if ALL to be written). Each signal is stored
in a separate extension.
- String containing the name of the file to be
- String defining the signal coefficients to read
Valid options: 'T', 'E', 'B' or 'ALL'
- String array containing the primary header read from the FITS
- If set, the routine documentation header is shown and the routine exits
- Largest l multipole to be output
- Smallest l multipole to be output. If LMIN (resp. LMAX) is below (above) the range of l's present in the file,
it will be silently ignored
- String array containing the read extension header(s). If
ALL signals are required, then the three extension
headers are returned appended into one string array.
fits2alm reads binary table extension(s)
which contain the alm coefficients (and associated errors if present)
from a FITS file. FITS headers can also optionally be read from the
This section lists the routines related to fits2alm
- version 6.4 or more is necessary to run fits2alm.
- provides the complimentary routine to write
alm coefficients into a FITS file.
- these facilities turn indexed lists of alm into 2D a(l,m) tables and back
- converts the index i = l2 +
l + m + 1 returned by fits2alm into l and m
- converts (l, m) vectors into i = l2 +
l + m + 1
- routine to read/compute C(l) power spectra from a file containing C(l) or alm coefficients
- IDL routine providing alm coefficients file to be read by fits2alm.
alteralm, anafast, synfast
- F90 facilities providing alm coefficients file to be read by fits2alm.
fits2alm reads from the input FITS file alm.fits
the alm coefficients into the variable alm with optional headers
passed by the string variables hdr and xhdr. Upon return index
will contain the value of l2 + l + m + 1 for each alm
found in the file.
Version 3.31, 2017-01-06