desc.equilibrium.Equilibrium.map_coordinates

Equilibrium.map_coordinates(coords, inbasis, outbasis=('rho', 'theta', 'zeta'), guess=None, params=None, period=(inf, inf, inf), tol=1e-06, maxiter=30, full_output=False, **kwargs)Source

Transform coordinates given in inbasis to outbasis.

Solves for the computational coordinates that correspond to inbasis, then evaluates outbasis at those locations.

Performance can often improve significantly given a reasonable initial guess.

Parameters:

  • coords (ndarray) – Shape (k, 3). 2D array of input coordinates. Each row is a different point in space.

  • inbasis (tuple of str) – Labels for input and output coordinates, e.g. (“R”, “phi”, “Z”) or (“rho”, “alpha”, “zeta”) or any combination thereof. Labels should be the same as the compute function data key.

  • outbasis (tuple of str) – Labels for input and output coordinates, e.g. (“R”, “phi”, “Z”) or (“rho”, “alpha”, “zeta”) or any combination thereof. Labels should be the same as the compute function data key.

  • guess (jnp.ndarray) – Shape (k, 3). Initial guess for the computational coordinates [‘rho’, ‘theta’, ‘zeta’] corresponding to coords in inbasis. If not given, then heuristics based on inbasis or a nearest neighbor search on a grid may be used. In general, this must be given to be compatible with JIT.

  • params (dict) – Values of equilibrium parameters to use, e.g. eq.params_dict.

  • period (tuple of float) – Assumed periodicity for each quantity in inbasis. Use np.inf to denote no periodicity. Default is no periodicity.

  • tol (float) – Stopping tolerance.

  • maxiter (int) – Maximum number of Newton iterations.

  • full_output (bool, optional) – If True, also return a tuple where the first element is the residual from the root finding and the second is the number of iterations.

  • kwargs (dict, optional) – Additional keyword arguments to pass to root such as maxiter_ls, alpha.

Returns:

  • out (jnp.ndarray) – Shape (k, 3). Coordinates mapped from inbasis to outbasis. Values of NaN will be returned for coordinates where root finding did not succeed, possibly because the coordinate is not in the plasma volume.

  • info (tuple) – 2 element tuple containing residuals and number of iterations for each point. Only returned if full_output is True.