def _calculateBVector(self, date, coordinate):
"""
Given a date, and a coordinate, calculate the value of the B-field.
@param date (\a float) the decimal year at which to calulate the B-field
@param coordinate (\a isceobj.Location.Coordinate) the location at which to calculate the B-field
@return (\a list) the north, east and down values of the B-field in gauss
"""
from ctypes import cdll, c_float, c_char_p
lib = cdll.LoadLibrary(os.path.dirname(__file__) + '/issi.so')
year = DTU.dateTimeToDecimalYear(date)
year_c = c_float(year)
lat_c = c_float(coordinate.getLatitude())
lon_c = c_float(coordinate.getLongitude())
alt_c = c_float(coordinate.getHeight())
beast_c = (c_float * 1)(*[0.0])
bnorth_c = (c_float * 1)(*[0.0])
bdown_c = (c_float * 1)(*[0.0])
babs_c = (c_float * 1)(*[0.0])
dataPath_c = c_char_p(dataPath) # Point to the library directory
lib.calculateBVector(year_c, lat_c, lon_c, alt_c, beast_c, bnorth_c,
bdown_c, babs_c, dataPath_c)
beast = beast_c[0]
bnorth = bnorth_c[0]
bdown = bdown_c[0]
return [beast, bnorth, bdown]
def testDateTimeToDecimalYear(self):
ans = 2004.2053388
decimalYear = DateTimeUtil.dateTimeToDecimalYear(self.dt1)
self.assertAlmostEquals(decimalYear, ans, 5)
