import math
#Robert Grumbine
#1 June 2018

class const:
    rpdg           = math.pi / 180.
    dgpr           = 180. / math.pi

    earth_radius   = 6371.2   # km -- sphere
    earth_spheroid = 6378.137 # km -- oblate spheroid (WGS84)
    eccen2         = 0.00669438
#Computed parameters
    eccen        = math.sqrt(eccen2)
    ps_chi1  = ( eccen2/2. + 5.*eccen2*eccen2/24. + eccen2*eccen2*eccen2/12.);
    ps_chi2  = ( 7.*eccen2*eccen2/48. + 29.*eccen2*eccen2*eccen2/240.);
    ps_chi3  = ( 7.*eccen2*eccen2*eccen2/120. );
    ps_ll    = math.pow( math.pow(1.+eccen,1.+eccen) * math.pow(1.-eccen,1.-eccen) , 1./2.);

#from 
##ifdef WGS84
#  const double parameters::rearth  = 6378.137e3;
#  const double parameters::eccen2 = 0.00669438;
#  #define ECCEN2 0.00669438
##else
#  const double parameters::rearth  = 6378.160e3; //earth definition is from
#  const double parameters::eccen2 = 0.006694604; //GRIB standard
#  #define ECCEN2 0.006694604
##endif