program ex2_3
! p2_3.f90 1.1 2014/02/09
! $Id: 2.3.f90 1.3 2025/07/13 09:35:12 s Exp $

implicit none
character(len = 20) fm1, fm2
integer n
real(8) er_percent, r

! r  : nominal rate
! n  : a number of months
! er_percent : effective interset rate in percent 

! input
r = 0.03d0
n = 12

! calculation
er_percent = ((1.0d0 + r / 12.0d0) ** n - 1.0d0) * 100.0d0

! output
fm1 = '(a10,f10.2)'
fm2 = '(a10,i10)'
write(*,*)   '2.3.f90'
write(*,fm1) 'r=', r
write(*,fm2) 'n=', n
write(*,fm1) 'er(%)=', er_percent
end program ex2_3
! end