healpy.fitsfunc.read_alm

healpy.fitsfunc.read_alm(filename, hdu=1, return_mmax=False)

Read alm from a fits file.

In the fits file, the alm are written with explicit index scheme, index = l**2+l+m+1, while healpix cxx uses index = m*(2*lmax+1-m)/2+l. The conversion is done in this function.

Parameters:

filenamestr or HDUList or HDU or pathlib.Path instance

The name of the fits file to read

hduint, or tuple of int, optional

The header to read. Start at 0. Default: hdu=1

return_mmaxbool, optional

If true, both the alms and mmax is returned in a tuple. Default: return_mmax=False

Returns:

alms[, mmax]complex array or tuple of a complex array and an int

The alms read from the file and optionally mmax read from the file