program integration_with_doloop
! 
! This program computes the numerical integration of cosine function
!
! Written by: Kadin Tseng
! Date written: September 19, 2012
!
implicit none
real, parameter :: pi=3.141593
real :: a, b, h, integ, integral
integer :: n, m
a = 0.0              ! lower limit of integration
b = pi/2             ! upper limit of integration
do n=1,4             ! number of cases to study
   !m = 25*2**(n-1) ! define number of increments as a function of n
   m = 25*2**n       ! define number of increments as a function of n
   h = (b - a)/m     ! increment length
   integ = integral(a, h, m)  ! perform integration
   print*, 'No. of increments = ',m,'  Integral value is ', integ
enddo
end program integration_with_doloop