distribution_gaussian.F90

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!! Copyright (C) 2024 M. Lueders
!!
!! This Source Code Form is subject to the terms of the Mozilla Public
!! License, v. 2.0. If a copy of the MPL was not distributed with this
!! file, You can obtain one at https://mozilla.org/MPL/2.0/.
!!
#include "global.h"
 
 
module distribution_gaussian_oct_m
 
  use, intrinsic :: iso_fortran_env
  use global_oct_m
  use namespace_oct_m
  use quickrnd_oct_m
 
  implicit none
 
  private
  public ::      &
    normal_distribution_get_random
 
 
contains
 
 
  !
  function normal_distribution_get_random(seed, n) result(values)
    integer(int64), intent(inout) :: seed
    integer,        intent(in)    :: n
 
    real(real64) :: values(1:n, 1:2)
 
    real(real64) :: flat(1:2*n)
    real(real64) :: R(n), Theta(n)
 
    call shiftseed(seed, 1000_int64)
    call quickrnd(seed, 2*n, flat)
 
    r = sqrt(-2.0_real64 * log(1.0_real64 - flat(1:n)))
    theta = 2.0_real64 * m_pi * flat(n+1:2*n)
 
    values(:,1) = r * cos(theta)
    values(:,2) = r * sin(theta)
 
  end function normal_distribution_get_random
 
 
end module distribution_gaussian_oct_m