def __init__(self, magnitude=STANDARD_GRAVITY):
"""
Construct field model.
@param magnitude: Magnitude of field in m/s^2. Default is standard
Earth gravity.
"""
ConstantVectorField.__init__(self, vector(0, 0, magnitude))
def __init__(self, magnitude=STANDARD_GRAVITY):
"""
Construct field model.
@param magnitude: Magnitude of field in m/s^2. Default is standard
Earth gravity.
"""
ConstantVectorField.__init__(self, vector(0, 0, magnitude))
def __init__(self, magnitude=50e-6, inclination=70, declination=0):
"""
Construct field model.
Default parameters result in a field with a magnitude of 50
microTesla, a 70 degree downwards inclination and 0 degrees
declination. These defaults are based on the nominal values for
Edinburgh, UK, with declination set to 0 degrees so that magnetic
and true North are equivalent.
@param magnitude: Magnitude of the field, in Teslas.
@param inclination: Inclination of the field to the horizontal,
in degrees.
@param declination: Delcination of the field from true North,
in degrees.
"""
theta = math.radians(declination)
ctheta = math.cos(theta)
stheta = math.sin(theta)
phi = math.radians(inclination)
cphi = math.cos(phi)
sphi = math.sin(phi)
value = magnitude * vectors.vector(cphi*ctheta, cphi*stheta, sphi)
ConstantVectorField.__init__(self, value)
