! Module file: getfom
!
! CNS module
! **********
!
! Authors: Piet Gros and Axel T. Brunger
!
! copyright Yale University
!
! Function:
! Compute M: complex structure factor, amplitude: figure of merit and
! phase: centroid phase. 
!
! Requirements:
! 1. This module can only be called from xray
! 2. Probability must be precomputed, supplied in Hendrickson & Lattman 
!    coefficients
!

module {getfom}
(
   &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}

   &m=m;                {complex: amplitude: figure-of-merit, phase: centroid phase}

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

   &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 (&m=get_fom[phistep=&phistep,CEN360=&cen360](&pa,&pb,&pc,&pd) ) ( &sel )

!
!                {*normalize probability*}
!
!@@normalizeprobability
!           (
!            sel=sel;
!            pk=pk;
!            pa=pa;pb=pb;pc=pc;pd=pd;
!            phistep=phistep;
!            cen360=&cen360;
!           )
! 
!                {*compute complex fom*}
!
!do (m=
!    (combine(1,centric_phase)*
!     (
!      exp
!      (
!       pk+pa*cos(centric_phase)+pb*sin(centric_phase)
!      )
!      -exp
!      (
!       pk-pa*cos(centric_phase)-pb*sin(centric_phase)
!      )
!     )
!    )
!   )   ( (not &cen360) and centric and sel)
!
!do (m=
!    (integrate[_phi,0,360,phistep]
!     (combine(1,_phi)*
!      exp
!      (
!       pk+pa*cos(_phi)+pb*sin(_phi)+pc*cos(2*_phi)+pd*sin(2*_phi) 
!      )
!     )
!    )
!   )   (( &cen360 or acentric) and sel)
!
!
!