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