Source code for irfpy.mars.mpb

''' Magnetic pileup boundary (MPB) model.

Usage:

>>> from irfpy.mars import mpb
>>> mpb_model = mpb.MpbVignes.mpb_xr()

This will return the Vignes's MPB model in X-R coordinates (as [2, 180] shaped matrix).

'''

import numpy as np

class MpbVignes:

    @classmethod
    def mpb_xr(self):
        ''' Return the magnetic pileup boundary position.

        :returns: The array with shape of (2, 180).  Unit is in Rm.

        >>> print(MpbVignes.mpb_xr()[:, 50])
        [1.16947853 0.46878494]
        '''
        L = 0.96
        e = 0.90
        x0 = 0.78

        theta = np.linspace(0, 180 * np.pi / 180., 180)
        r = L / (1 + e * np.cos(theta))

        x = r * np.cos(theta) + x0
        y = r * np.sin(theta)

        return np.array([x, y])


    @classmethod
    def inside(self, x, y, z):
        ''' Return if the s/c is in MPB

        >>> print(MpbVignes.inside(1, 0, 0))
        True
        >>> print(MpbVignes.inside(0, 2, 0))
        False
        '''
        L = 0.96
        e = 0.90
        x0 = 0.78

        xx = x - x0
        yy = np.sqrt(y ** 2 + z ** 2)

        theta = np.arctan2(yy, xx)

        rr2 = xx ** 2 + yy ** 2

        rb = L / (1 + e * np.cos(theta))
        rb2 = rb ** 2

        return rr2 < rb2

import unittest
import doctest


def doctests():
    return unittest.TestSuite((
        doctest.DocTestSuite(),
        ))
if __name__ == '__main__':
    unittest.main(defaultTest='doctests')