supercreen-field-from-solution.py

supercreen-field-from-solution.py

import numpy as np
import superscreen as sc

def field_from_solution(
    x: np.ndarray,
    y: np.ndarray,
    z: np.ndarray,
    *,
    solution: sc.Solution,
    dr: tuple[float, float, float] = (0.0, 0.0, 0.0),
    units: str = "mT",
) -> np.ndarray:
    """Evaluates the z-component of the screening field from a ``superscreen.Solution``.
    
    Args:
      x: The x values at which to evaluate the field, shape ``(n,)``
      y: The y values at which to evaluate the field, shape ``(n,)``
      z: The z values at which to evaluate the field, shape ``(n,)``
      solution: The ``superscreen.Solution``
      dr: The relative position between the coordinate system for ``solution.device``
          and the coordinate system for the target ``superscreen.Device``
      units: The magnetic field units in which to return the field
      
    Returns:
        B_z due to screening currents flowing in ``solution.device``, evaluated
        at positions ``[x, y, z]``  in the specified units, shape ``(n, )``
    """
    x = np.squeeze(x)
    y = np.squeeze(y)
    z = np.squeeze(z)
    if z.ndim == 0:
        z = z.item() * np.ones_like(x)
    positions = np.array([x, y, z]).T - np.array([dr])
    return solution.screening_field_at_position(
        positions, units=units, with_units=False
    )

Usage:

sample_solution = sc.solve(
    sample_device,
    applied_field=sc.Parameter(
        field_from_solution,
        solution=squid_solution,
        dr=squid_position,
    ),
    field_units="mT",
)[-1]