ring_analysis
This subroutine computes the Fast Fourier Transform of a single ring
of pixels
and extends the computed coefficients up to the maximum
of the transform.
Location in HEALPix directory tree: src/f90/mod/alm_tools.F90
FORMAT
ARGUMENTS
name & dimensionality |
kind |
in/out |
description |
|
|
|
|
nsmax |
I4B |
IN |
of the map. |
nlmax |
I4B |
IN |
Maximum of the analysis. |
nmmax |
I4B |
IN |
Maximum of the analysis. |
nph |
I4B |
IN |
The number of points on the ring. |
datain(0:nph-1) |
DP |
IN |
Function values on the ring. |
dataout(0:nmmax) |
DPC |
OUT |
Fourier components, replicated to . |
kphi0 |
I4B |
IN |
0 if the first pixel on the ring is at
; 1 otherwise. |
EXAMPLE:
call ring_analysis(64,128,128,datain,8,dataout,0)
Returns the periodically extended complex
Fourier Transform of datain in
dataout. They are returned in the following order: 0 1 2 3 4 5 6 7
6 5 4 3 2 1 . The value specifies that no phase
factor needed to be applied, because the ring starts at .
MODULES & ROUTINES
This section lists the modules and routines used by ring_analysis.
-
healpix_fft
- module.
RELATED ROUTINES
This section lists the routines related to ring_analysis
-
ring_synthesis
- Inverse transform (complex-to-real), used in
alm2map,
alm2map_der and synfast
Version 3.82, 2022-07-28