= Ex12sq.f90 = {{{#!fortran ! ! Fortran sample ! ex12sq.f90 ! Approximate PI-3.14159265.... ! with Leibniz Formula program approximate_pi implicit none integer :: i,n double precision :: x character(len=32) :: arg ! Newer version of Fortran can get commadline arguments call get_command_argument(1,arg) if (len_trim(arg) == 0) then call get_command_argument(0,arg) print *,arg," [number of terms]" call exit(-1) end if ! convert string to integer read(arg,*) n print *,"Start n=",n x=0.d0 ! sum do i = 0, n, 2 x = x + 1.d0 / (2.d0 * dble(i) + 1.d0); x = x - 1.d0 / (2.d0 * dble(i) + 3.d0); end do print *,"n=",n,"Pi=",4.d0 * x end program approximate_pi }}}