! Module file: normalizeprobability
!
! CNS module
! **********
!
! Authors: Piet Gros and Axel T. Brunger
!
! copyright Yale University
!
! Function:
! Normalize phase probability. Note: the normalization is dependent on
! the size of the phase step in the integration.
!
! Requirements:
! 1. This module can only be called called from xray
! 2. Probability must be supplied in Hendrickson & Lattman coefficients
!

module {normalizeprobability}
(
   &messages="off";	

   &sel=(all);      {structure factor selection}

   &pk=pk;          {Hendrickson and Lattman K array, i.e.-log normalization factor}
   &pa=pa;          {Hendrickson and Lattman A array}
   &pb=pb;          {Hendrickson and Lattman B array}
   &pc=pc;          {Hendrickson and Lattman C array}
   &pd=pd;          {Hendrickson and Lattman D array}

   &phistep=20;     {size of phase steps in integration}

   &cen360=FALSE; { TRUE | FALSE (type logical); if TRUE a full 0...360 phase prob. distr. }
                  { is used for centric reflections (useful if the "native"                }
                  { structure factor has an anomalous signal).                             }
)

checkversion 1.3

do (&pk=get_norm[phistep=&phistep,CEN360=&cen360](&pa,&pb,&pc,&pd)) (&sel)

!                {*Normalize*}
!
!do (work=0) (all)                               {avoid numerical overflow}
!do (work=
!    max
!    (
!     (pa*cos(centric_phase)+pb*sin(centric_phase)),
!     (-pa*cos(centric_phase)-pb*sin(centric_phase))
!    )
!   ) ( (not &cen360) and centric and sel)
!do (work=
!    maximize[_phi,0,360,phistep]
!    (
!     pa*cos(_phi)+pb*sin(_phi)+pc*cos(2*_phi)+pd*sin(2*_phi)
!    )
!   ) (( &cen360 or acentric) and sel)
!
!do (pk=                                        {normalize}
!    exp
!    (
!     pa*cos(centric_phase)+pb*sin(centric_phase)
!     -work
!    )
!    +exp
!    (
!     -pa*cos(centric_phase)-pb*sin(centric_phase)
!     -work
!    )
!   )   ((not &cen360) and centric and sel)
!do (pk=
!    integrate[_phi,0,360,phistep]
!    (exp
!     (
!      pa*cos(_phi)+pb*sin(_phi)+pc*cos(2*_phi)+pd*sin(2*_phi)-work
!     )         
!    )
!   )   (( &cen360 or acentric) and sel)
!