Category Archives: Fortran

Euler problem 11.4

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recursive function max_e11(a2d, i, j, acc) result(a)

  integer, dimension(20, 20) :: a2d
  integer :: i, j, acc, a, accm = 0
  integer :: dia_l = 0, dia_r = 0, hori = 0, vert = 0
  integer :: k = 0, x = 1, y = 1
  integer :: lenx = 20, leny = 20

  if (i <= (lenx - 3)) then 
     hori = 1
     do k = 0, 3 
        hori = hori*a2d(i+k, j)
     end do
  end if

  if (j <= (leny - 3)) then
     vert = 1
     do k = 0, 3 
        vert = vert*a2d(i, j+k)
     end do
  end if

  if ((i <= (lenx - 3)) .and. (j <= (leny - 3))) then
     dia_r = 1
     do k = 0, 3 
        dia_r = dia_r*a2d(i+k, j+k)
     end do
  end if

  if ((i >= 4) .and. (j <= (leny - 3))) then
     dia_l = 1
     do k = 0, 3
        dia_l = dia_l*a2d(i-k, j+k)
     end do
  end if

  if ((i == lenx) .and. (j == leny)) then 
     a = acc
  else 
     accm = max(acc, hori, vert, dia_l, dia_r)

     if (i == lenx) then
        x = 1
        y = j + 1
     else 
        x = i + 1
        y = j
     end if

     a = max_e11(a2d, x, y, accm)
  end if
end function max_e11

program main

  implicit none

  integer :: p_max, p_count, i, j
  integer(kind = 16) :: p_sum
  logical, ALLOCATABLE, DIMENSION(:) :: is_prime
  character(len=128) :: currentDir
  integer, dimension(20, 20) :: D, M
  integer :: max_e11

  call GET_ENVIRONMENT_VARIABLE('PWD', currentDir)

  print *, "dir == ", trim(currentDir)

  open(1, file = "t.txt", status = "old")
  read(1, *) D
  close(1)

  M = transpose(D)

  write(*, *) M(1, 1)
  write(*, *) max_e11(M, 1, 1, 0) 
  write(*, *) M(1, 1)

end program main

— Me@2022-12-24 11:50:15 AM

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2022.12.24 Saturday (c) All rights reserved by ACHK

Fortran Package Manager

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Haskell mode, 3

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The goal of this blog post is to set up an integrated programming environment for Fortran.

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1. Read and follow the exact steps of my post titled “Haskell mode“.

2. Read and follow the exact steps of my post titled “Haskell mode, 2“.

3. Install the package manager Anaconda.

4. Use Anaconda to install the Fortran Package Manager (fpm), by following the fpm installation guide.

4.1. Add the additional channel mentioned in the fpm installation guide.

4.2. Install the fpm itself:

conda create -n fpm_env fpm

conda activate fpm_env

5. Install the Fortran language server:

conda install fortls

6. Install the Emacs plugin:

sudo apt-get install elpa-pyvenv

7. Open Emacs’ initialization file, whose location should be

~/.emacs

8. Add the following code to the file.


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun gfortran-run ()

  (interactive)

  (save-buffer)

  (unless visual-line-mode
    (visual-line-mode 1))

  (universal-argument)

  (compile "fpm run"))

(global-set-key (kbd "C-x C-r") 'gfortran-run)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(setenv "WORKON_HOME" "~/anaconda3/envs")

(pyvenv-mode 1)

(pyvenv-workon "fpm_env")

;;;;;;;;;;;;;;;;;;;;;;;;;;;

(add-hook 'f90-mode-hook #'lsp)

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

— Me@2022-12-01 09:18:59 AM

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2022.12.04 Sunday (c) All rights reserved by ACHK

Why does the universe exist? 7.3

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Euler problem 10.4

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program main

  implicit none

  integer :: p_max, p_count, i, j
  integer(kind = 16) :: p_sum
  logical, ALLOCATABLE, DIMENSION(:) :: is_prime

  p_max = 2000000

  ALLOCATE(is_prime(p_max))

  is_prime = .true.

  is_prime(1) = .false.

  do i = 2, ceiling(sqrt(real(p_max)))
     if (is_prime(i)) then
        do j = i*i, p_max, i
           is_prime(j) = .false.
        end do
     end if
  end do

  p_count = 0
  p_sum = 0
  do i = 1, p_max
     if (is_prime(i)) then
        p_count = p_count + 1
        p_sum = p_sum + i
     end if
  end do

  print *, "p_count == ", p_count
  print *, "p_sum == ", p_sum

  DEALLOCATE(is_prime)

end program main

For a universe part, which is partial in space or in time, you can ask for its cause.

But for the universe as a whole, you cannot.

If the big bang is the first cause, you cannot ask for the cause of its existence.

Asking for the cause of the existence of the universe is the same as asking for the cause of the first cause.

— Me@2012-10-15 08:33:01 AM

— Me@2022-11-27 09:09:53 PM

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2022.12.04 Sunday (c) All rights reserved by ACHK