spectre.converters.compute_guesses_map2disc
===========================================

.. py:module:: spectre.converters.compute_guesses_map2disc

.. autoapi-nested-parse::

   ``map2disc`` (BCM) interface guesses from boundary Fourier coefficients.

   The :mod:`map2disc` package provides a 2-D boundary-conformal map (``BCM``) that
   maps the unit disc onto an arbitrary poloidal cross-section.  By evaluating the
   map at radii ``rho = sqrt(tflux)`` it produces geometrically smooth *nested*
   interfaces inside a given plasma boundary.

   This module holds the converter-side entry point
   :func:`compute_interface_guesses_map2disc`, which maps a boundary given directly
   as Fourier-coefficient dicts (no SPECTRE object required).  The actual conformal
   mapping loop lives in :func:`spectre.mesh_gen.map2disc.map_boundary_to_interfaces`
   and is shared with the SPECTRE-state mesh generation in
   :mod:`spectre.mesh_gen`.





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

.. py:function:: compute_interface_guesses_map2disc(rbc, zbs, nfp, tfluxes, mpol, ntor, ntheta=124, nzeta=78, bcm_m=6)

   Generate interface geometry guesses using conformal mapping (map2disc).

   Uses the ``map2disc`` BCM solver to conformally map the plasma boundary
   inward to each interface position, producing geometrically smooth nested
   surfaces.  Only the boundary Fourier harmonics are required — no VMEC wout
   or SPECTRE object is needed — so this works from both ``input.*`` and
   ``wout_*.nc`` sources.

   The ``rbc`` / ``zbs`` dicts must be in SPECTRE convention (angle-fix applied,
   i.e. the output of :func:`~spectre.converters.vmec_helpers.vmec_boundary_to_fourier_coeffs`
   with ``angle_fix=True``).  The same sign convention (``th_arr = -th_arr``) as
   :func:`~spectre.mesh_gen.generators.gen_infaces` is used internally so the FFT
   output is directly compatible with ``allrzrz``.

   Args:
       rbc: boundary R cosine harmonics as ``{'(m, n)': value}`` dict
           (SPECTRE convention, angle-fix applied).
       zbs: boundary Z sine harmonics as ``{'(m, n)': value}`` dict
           (SPECTRE convention, angle-fix applied).
       nfp: number of toroidal field periods.
       tfluxes: 1-D array of interface toroidal-flux values in (0, 1].
       mpol: maximum poloidal mode number for the output.
       ntor: maximum toroidal mode number (reduced, without nfp) for the output.
       ntheta: number of poloidal quadrature points (default 124).
       nzeta: number of toroidal quadrature points per field period (default 78).
       bcm_m: number of Fourier modes used by BCM (default 6).

   Returns:
       dict suitable for ``PhysicsParameters.allrzrz``:
       ``{'interface_1': {'rbc': {...}, 'zbs': {...}, 'rbs': {...}, 'zbc': {...}},
       ...}``

   Raises:
       ImportError: if ``map2disc`` is not installed.