Integer Function aphindex(totaltheta,totalchi,rhopt,thetapt,chipt,reflect)
Implicit None

!=================================================================
! Function to compute APH vector component indices.
! The function name must be declared as an integer in the routine
!     in which it is called.

Logical reflect
Integer,Intent(IN):: totaltheta,totalchi
Integer,Intent(IN):: rhopt,thetapt,chipt

! To pick points in nonreactive channel ( chi=0 to 30 degrees )

IF (.not.reflect) THEN

  aphindex=totalchi*totaltheta*(rhopt-1)+totalchi*(thetapt-1)+chipt

! To pick points in reactive channel ( chi=30 to 60 degrees )

ELSEIF (reflect) THEN

  aphindex=totalchi*totaltheta*(rhopt-1)+totalchi*(thetapt-1)+(totalchi-chipt+1)

ELSE

  aphindex=0
  PRINT*,'INCORRECT value for argument 6 (logical) in aphindex '
  STOP 'aphindex'

ENDIF

End Function aphindex