PROGRAM PopulationMod
!--------------------------------------------------------------------------------------------
!Karl Harris                                   ENGR 225                        1-27-12
!
!This program will calculate population growth over time
!
!Identifiers used are:
!PT            : Population growth over time (in years)
!time          : time of growth (in years)
!PO            : Initial Population
! b            : Birth Rate
!d             : Death Rate
!--------------------------------------------------------------------------------------------
IMPLICIT NONE
INTEGER, PARAMETER :: dp=selected_real_kind (15)   !15 sig figs
Real(dp) :: PT, PO, b, d, t

!Get Initial population,birth rate, death rate,and time
Write(*,*)"Pleas enter Initial population,birth rate, death rate,and time."
Read(*,*) PO, b, d, t

!Calculate population growth over time
PT=PO*exp((b-d)*t)

Write(*,*) "The population growth over",t,"years is",PT
STOP

END PROGRAM PopulationMod