89 lines
2.7 KiB
Plaintext
89 lines
2.7 KiB
Plaintext
|
! Provides a subroutine to build Pascal's triangle
|
||
|
!
|
||
|
! Copyright © 2021 Dynare Team
|
||
|
!
|
||
|
! This file is part of Dynare.
|
||
|
!
|
||
|
! Dynare is free software: you can redistribute it and/or modify
|
||
|
! it under the terms of the GNU General Public License as published by
|
||
|
! the Free Software Foundation, either version 3 of the License, or
|
||
|
! (at your option) any later version.
|
||
|
!
|
||
|
! Dynare is distributed in the hope that it will be useful,
|
||
|
! but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
|
! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
|
! GNU General Public License for more details.
|
||
|
!
|
||
|
! You should have received a copy of the GNU General Public License
|
||
|
! along with Dynare. If not, see <https://www.gnu.org/licenses/>.
|
||
|
|
||
|
module pascal
|
||
|
implicit none
|
||
|
|
||
|
type line
|
||
|
integer, dimension(:), allocatable :: coeffs
|
||
|
end type line
|
||
|
|
||
|
type pascal_triangle
|
||
|
integer :: d
|
||
|
type(line), dimension(:), allocatable :: lines
|
||
|
end type pascal_triangle
|
||
|
|
||
|
interface pascal_triangle
|
||
|
module procedure :: init_pascal_triangle
|
||
|
end interface pascal_triangle
|
||
|
|
||
|
contains
|
||
|
|
||
|
! Fills a pascal_triangle structure with the associated coefficients up to a given order
|
||
|
type(pascal_triangle) function init_pascal_triangle(d)
|
||
|
integer, intent(in) :: d
|
||
|
integer :: i, j
|
||
|
init_pascal_triangle%d = d
|
||
|
allocate(init_pascal_triangle%lines(d))
|
||
|
! Initializing the first line
|
||
|
allocate(init_pascal_triangle%lines(1)%coeffs(2))
|
||
|
init_pascal_triangle%lines(1)%coeffs = 1
|
||
|
! Iterating Pascal's triangle formula
|
||
|
if (d > 1) then
|
||
|
do i=2,d
|
||
|
allocate(init_pascal_triangle%lines(i)%coeffs(i+1))
|
||
|
init_pascal_triangle%lines(i)%coeffs(1) = 1
|
||
|
init_pascal_triangle%lines(i)%coeffs(i+1) = 1
|
||
|
do j=2,i
|
||
|
init_pascal_triangle%lines(i)%coeffs(j) = init_pascal_triangle%lines(i-1)%coeffs(j-1) &
|
||
|
+ init_pascal_triangle%lines(i-1)%coeffs(j)
|
||
|
end do
|
||
|
end do
|
||
|
end if
|
||
|
end function init_pascal_triangle
|
||
|
|
||
|
! Returns ⎛n⎞ stored in pascal_triangle p
|
||
|
! ⎝k⎠
|
||
|
|
||
|
type(integer) function get(k,n,p)
|
||
|
integer, intent(in) :: k, n
|
||
|
type(pascal_triangle), intent(in) :: p
|
||
|
get = p%lines(n)%coeffs(k+1)
|
||
|
end function get
|
||
|
|
||
|
end module pascal
|
||
|
|
||
|
! gfortran -o pascal pascal.f08
|
||
|
! ./pascal
|
||
|
! program test
|
||
|
! use pascal
|
||
|
! type(pascal_triangle) :: p
|
||
|
! integer :: d
|
||
|
! read *, d
|
||
|
! p = pascal_triangle(d)
|
||
|
! do n=1,d
|
||
|
! do k=0,n
|
||
|
! if (k < n) then
|
||
|
! write (*,'(i2," ")', advance="no") get(k,n,p)
|
||
|
! else
|
||
|
! write (*,'(i2," ")') get(k,n,p)
|
||
|
! end if
|
||
|
! end do
|
||
|
! end do
|
||
|
! end program test
|