import numpy as np
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[docs]
def wnorm(phi, A=6378137.0, E2=0.006694380022903):
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"""
Calculate the geodetic radius of curvature normal to the ellipsoid.
Parameters
----------
phi : float or ndarray
Geodetic latitude in radians.
A : float, optional
Semi-major axis of the ellipsoid (default WGS84 in m).
E2 : float, optional
First eccentricity squared (default WGS84).
Returns
-------
float or ndarray
Radius of curvature (m).
"""
a = A
e2 = E2
wd = np.sqrt(1.0 - e2 * np.sin(phi) ** 2)
result = a / wd
return result