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.
- 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
- 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