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 ${N_{\rm side}}$ of the map.
nlmax I4B IN Maximum l 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 alm.
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 ${N_{\rm side}}=64$. 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

Version 3.31, 2017-01-06