& (exf_one + xsq)/8.) - exf_two*atan(x) +
& *( atan( -( rF(k)-diffKrBL79Ho )/diffKrBL79scl )/PI+0.5 _d 0)
& 2. _d 0*atan(x) + pi*.5 _d 0)
pi = 4.0*atan(1.0)
PI = 4.*atan(1.)
. ((atan( (2.*(pcheck-pup)/(ppbl-pup)-1.) *
pi = 4.*atan(1.)