healpix_analyse.LocalizedFlatSkyAlm
===================================

.. py:module:: healpix_analyse.LocalizedFlatSkyAlm

.. autoapi-nested-parse::

   LocalizedFlatSkyAlm.py

   Modified from LocalizedAlm_optimized_v13_fixed.py.
   - Removed exact Y_lm (Legendre Polynomial) precomputation to solve RAM explosion at high N_side.
   - Implements Phase-Aligned Flat-Sky Approximation using a 2D FFT (1D Longitude + 1D Latitude).
   - Isotropically bins the 2D Cartesian power spectrum into 1D multipoles (ell).



Classes
-------

.. autoapisummary::

   healpix_analyse.LocalizedFlatSkyAlm.LocalizedFlatSkyAlm


Module Contents
---------------

.. py:class:: LocalizedFlatSkyAlm(level, patch_idx_ring, backend, lmax=None, lmax_compute=None)

   Bases: :py:obj:`foscat.alm.alm`


   Localized spherical harmonic analysis using a Phase-Aligned Flat-Sky FFT.
   Avoids O(lmax^2) memory bottlenecks for ultra-high resolution maps.


   .. py:attribute:: level


   .. py:attribute:: nside


   .. py:attribute:: patch_idx_ring


   .. py:attribute:: device


   .. py:attribute:: dtype


   .. py:attribute:: lmax_full


   .. py:attribute:: lmax_compute


   .. py:attribute:: active_shift_ph


   .. py:method:: comp_tf_localized(u_patch)

      Compute 1D Longitude FFT on active rings & apply phase alignment.



   .. py:method:: anafast_localized(u_patch, map2_patch=None, bandpowers_binning=None)

      Compute pseudo-Cl using a 2D Phase-Aligned Flat-Sky FFT.