Source code for irfpy.jdc.fov0

''' JDC fov module.

As of I know only little on JDC, I made this module for a draft use.
Thus, I added ``0`` in the trail of the module.

FOV 90x360 for each sensor with resolution of 5.5x19.5 means
the 16x16 separation, as a maximum, while I doubt such high number
of bins.  But for the draft purpose, I just implement following the
number. The implementation will be changed as the sensor design progresses.
'''
import numpy as np

def elev_pix_center(nel):
    r''' Elevation pixel center in degrees.

    The JDC has two units.  Number definition is, preliminary,
    0 to 15 for JDC on nadir unit and 16 to 31 for zenith.
    Ch-0 corresponds to the nadir-looking and 31 for zenith looking.

    The definition of angle, :math:`\theta` is 0 for zenith looking
    and 180 is nadir looking.
    
    Thus, the expression is

    .. math::

        \theta = (180. / 32.) * (31 - nel) + (180. / 64.)

    Note that the ``nel`` is usually ``int`` or ``np.array`` with
    ``dtype=np.int``, but ``float`` may be allowed for special use.


    :param nel: Number of elevation.  0 to 31.
    :type nel: ``int``, ``float`` or ``np.array``.
    :return: The elevation angle.
    :rtype: ``np.array``

    >>> print(elev_pix_center(0))
    177.1875
    >>> print(elev_pix_center(8))
    132.1875
    >>> print(elev_pix_center(31))
    2.8125
    >>> print(elev_pix_center([31, 23, 0]))
    [  2.8125  47.8125 177.1875]

    Note also that the returned type is np.array object, even
    the given parameter is a scalar.  In this case, np.array object
    with shape ``()`` is returned.

    >>> print(elev_pix_center(8).shape)
    ()
    '''
    return (180. / 32.) * (31.5 - np.array(nel))

def elev_pix_fwhm(nel):
    ''' Return the FWHM

    For draft, I just return 5.5 for simplicity.
    '''
    return 5.5 + np.zeros_like(nel)

def azim_pix_center(naz):
    r''' Return the azimuthal angle for the given channel number(s).

    Similar to :meth:`elev_pix_center`, the azimuthal angle,
    :math:`\phi` is returned.

    .. math::

        \phi = naz * 22.5 + 11.25

    >>> print(azim_pix_center(0))
    11.25
    >>> print(azim_pix_center(15))
    348.75
    >>> print(azim_pix_center([6, 7, 8]))
    [146.25 168.75 191.25]
    '''
    return np.array(naz) * 22.5 + 11.25

def azim_pix_fwhm(naz):
    ''' Return the FWHM

    For draft, I just return 19.5 for simplicity.
    '''
    return 19.5 + np.zeros_like(naz)
    
    


import unittest
import doctest


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