Replaced math.arccos() with math.acos(): difference nomenclature left over from numpy
Replaced math.arccos() with math.acos(): difference nomenclature left over from numpy

eayoungs/eppy,jamiebull1/eppy,jamiebull1/eppy,santoshphilip/eppy,eayoungs/eppy,jamiebull1/eppy,santoshphilip/eppy,santoshphilip/eppy,eayoungs/eppy