recip_DelIp = sign(1. _d 0,DelIp)/max(abs(DelIp),Eps)
Phi = Phi*recip_DelIp
rp1h = DelI*recip_DelIp
PhiMD = 1. _d 0/(1. _d 0-cfl)*(DelIp-dp1h)*recip_DelIp
_RL recip_DelIp, recip_DelI