ring_synthesis

Location in HEALPix directory tree: src/f90/mod/alm_tools.F90 

FORMAT

call ring_synthesis( nsmax, nlmax, nmmax, datain, nph, dataout, kphi0 )

ARGUMENTS

name & dimensionality	kind	in/out	description
nsmax	I4B	IN	$N_{\mathrm{side}}$ of the map.
nlmax	I4B	IN	Maximum $\ell$ of the analysis.
nmmax	I4B	IN	Maximum $m$ of the analysis.
nph	I4B	IN	The number of points on the ring.
datain(0:nmmax)	DPC	IN	Fourier components as computed from the $a_{lm}$.
dataout(0:nph-1)	DP	OUT	Synthesized function values on the ring.
kphi0	I4B	IN	0 if the first pixel on the ring is at $\phi=0$; 1 otherwise.

EXAMPLE:

call ring_synthesis(64,128,128,datain,8,dataout,1)

This computes the inverse (complex-to-real) Fast Fourier Transform for the second ring from the pole, containing $8$ pixels, for a map resolution of $N_{\mathrm{side}}=64$. $128$ complex Fourier compoments contribute to these 8 pixels. The value $kphi0=1$ specifies that a phase factor needed to be applied to correctly rotate the ring into position on the HEALPix grid.

MODULES & ROUTINES

This section lists the modules and routines used by ring_synthesis.

healpix_fft

module.

RELATED ROUTINES

This section lists the routines related to ring_synthesis

ring_analysis

Forward transform, used in map2alm and anafast