Segmentation error when passing a function as an argument in a subroutine

Question

Segmentation error when passing a function as an argument in a subroutine

I am trying to illustrate how to pass a function to the Newton Raphson procedure. I manage to execute a very simple function (called unefonctionsee below), but it does not work with a function that has parameters. This second highlight is called gaussienne, and it takes one argument, x and two optional arguments, muand sig. I called her so in my procedure Raphson newton: f(x). What is strange to me is that at run time the program does as if the optional parameters were present sigand mu, but they do not ... So, I don’t understand ...

Here is a module that contains functions

module fonction

  implicit none

  ! parametre pour la gaussienne
  double precision :: f_sigma = 1.d0, f_mu = 0.d0

  ! pi accessible uniquement en interne
  double precision, parameter :: pi = 3.14159265359d0

  contains

    double precision function unefonction(x)
        ! fonction : unefonction
        ! renvoie
        !    $\frac{e^x - 10}{x + 2}$

        implicit none

        ! arguments 
        double precision, intent(in) :: x

        unefonction = (exp(x) - 10.) / (x + 2.)

    end function unefonction

! * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * 

    double precision function gaussienne(x, mu, sig)
        ! fonction gaussienne
        ! utilise les parametres definis dans le module si
        ! mu et sig ne sont pas passes en argument

        implicit none

        ! arguments
        double precision, intent(in)           :: x
        double precision, intent(in), optional :: mu, sig

        ! variables locales
        double precision :: norme, moy, sigma

        ! sigma
        if (present(sig)) then
            write(*,*)"sig present"
            sigma = sig
        else
            sigma = f_sigma
        end if

        ! mu
        if (present(mu)) then
            write(*,*)"mu present"
            moy = mu
        else
            moy = f_mu
        end if

        ! calcul de la gaussienne
        norme = 1.d0 / (sigma * sqrt(2.d0 * pi))
        gaussienne = norme * exp(-(x - moy)**2 / (2.d0 * sigma**2))

    end function gaussienne

end module fonction

Here is the module that contains the newton raphson procedure

module rechercheRacine

    implicit none

    contains

        subroutine newtonRaphson(racine, f, eps, cible)

            ! recherche l'antecedant de cible

            implicit none

            ! arguments
            double precision, intent(inout)        :: racine
            double precision, intent(in), optional :: cible, eps

            ! fonction dont on cherche la racine
            double precision, external :: f

            ! variables locales
            integer          :: compteur
            double precision :: xold, xnew, delta, valcible
            double precision :: threshold, fprim, fdex

            ! precision
            if (present(eps)) then
                threshold = eps
            else
                threshold = 1.d-10
            end if

            ! valeur cible
            if (present(cible)) then
                valcible = cible
            else
                valcible = 0.d0
            end if

            write(*,*) "--------------------------------------------------------"
            write(*,*) "                      NEWTON RAPHSON"
            write(*,*) "--------------------------------------------------------"
            write(*,"('x0    = ',e16.6)") racine
            write(*,"('seuil = ',e16.6)") threshold
            write(*,"('cible = ',e16.6)") valcible
            write(*,*) "--------------------------------------------------------"
            write(*,*) "                        ITERATIONS"
            write(*,*) "--------------------------------------------------------"

            ! initialisation
            compteur = 0
            delta    = 1.d0
            xold     = racine
            write(*, '(i4,4e16.6)') compteur, f(xold), xold, 0., threshold

            ! iterations
            do while (delta > threshold .and. compteur <= 100)

                ! calcul de la fonction en xold
                fdex = f(xold) - valcible

                ! calcul de la derivee numerique
                fprim  = (f(xold + threshold) - f(xold - threshold)) / (2.d0 * threshold) 

                ! application de l'iteration de Newton Raphson
                xnew = xold - fdex / fprim
                delta = abs(xnew - xold)
                compteur = compteur + 1

                ! affichage de la convergence
                write(*, '(i4,4e16.6)') compteur, fdex, xnew, delta, threshold

                ! mise a jour de xstart
                xold = xnew
            end do

            if (delta < threshold) then
                racine = xnew
                write(*, *) '--------------------------------------------------------'
                write(*, *) '                        CONVERGE'
                write(*, *) '--------------------------------------------------------'
                write(*, *) 'A la convergence demandee, une solution est:'
                write(*, "('x = ',e20.10,'    f(x) = ', e20.10)") racine, f(racine)
                write(*, *)
            else
                write(*, *) '--------------------------------------------------------'
                write(*, *) '                      NON CONVERGE'
                write(*, *) '--------------------------------------------------------'
            end if

        end subroutine newtonRaphson

end module rechercheRacine

:

program main

    ! contient la subroutine newtonRaphson
    use rechercheRacine

    ! contient la fonction
    use fonction

    implicit none

    double precision :: racine, eps, cible

    ! appel de la subroutine newtonRaphson
    ! sans la valeur cible : cible (defaut = 0)
    ! sans la precision : eps (defaut 1d-10)
    racine = 1.d0
    call newtonRaphson(racine, unefonction)

    ! --------------------------------------------------------

    ! appel de la subroutine newtonRaphson
    ! avec pour cible 10
    racine = 1.d0
    eps    = 1.d-14
    cible  = 10.d0
    call newtonRaphson(racine, unefonction, eps, cible)

    ! --------------------------------------------------------

    ! parametre de la gaussienne
    f_sigma = 2.d0
    f_mu = 5.d0
    ! appel de la subroutine newtonRaphson
    ! passage des arguments sous la forme clef = valeur
    cible = 0.1d0
    racine = 2.d0
    call newtonRaphson(cible = cible, f = gaussienne, racine = racine)

end program main

unefonction, gaussienne.

:

Program received signal SIGSEGV: Segmentation fault - invalid memory reference.

Backtrace for this error:
#0  0x7F1B6F5890F7
#1  0x7F1B6F5896D4
#2  0x7F1B6EEEB49F
#3  0x4009D2 in __fonction_MOD_gaussienne at mod_fonction.f90:54
#4  0x40104D in __rechercheracine_MOD_newtonraphson at mod_racine.f90:59
#5  0x4016BA in MAIN__ at main.f90:40
Erreur de segmentation (core dumped)

, invalid memory reference , , sig mu, , .

+2

fortran

Ger 25 . '13 21:16

1

Bálint Aradi · Accepted Answer · 2013-02-25T21:53:12+0000

, , , , . external f newtonRaphson

double precision, external :: f

( , ):

interface
  double precision function f(x)
    double precision, intent(in) :: x
  end function f
end interface

- .

"" f, newtonRaphson:

, f intent(in) : x, , . :

interface
  double precision function f(x, params)
    double precision, intent(in) :: x
    double precision, intent(in) :: params(:)
  end function f
end interface

, (, unefonction), , (, gaussienne) .

newtonRaphson, (class) , x. , x , . ( ), Fortran 2003:

module rechercheRacine
  implicit none

  type, abstract :: calculator
  contains
    procedure(getvalue_iface), deferred :: getvalue
  end type calculator

  interface
    double precision function getvalue_iface(self, x)
      import :: calculator
      class(calculator), intent(in) :: self
      double precision, intent(in) :: x
    end function getvalue_iface
  end interface

contains

  subroutine newtonRaphson(racine, f, eps, cible)
    double precision, intent(inout)        :: racine
    class(calculator), intent(in)          :: f
    double precision, intent(in), optional :: cible, eps

    do while (delta > threshold .and. compteur <= 100)
      fdex = f%getvalue(xold) - valcible
      :
    end do

  end subroutine newtonRaphson

end module rechercheRacine


module fonction
  use rechercheRacine
  implicit none

  type, extends(calculator) :: unefonction
  contains
    procedure :: getvalue => unefonction_getvalue
  end type unefonction

  type, extends(calculator) :: gaussienne
    double precision :: mu = 0.0d0, sigma = 1.0d0
  contains
    procedure :: getvalue => gaussienne_getvalue
  end type gaussienne

contains

  double precision function unefonction_getvalue(self, x)
    class(unefonction), intent(in) :: self
    double precision, intent(in) :: x
    unefonction_getvalue = (exp(x) - 10.) / (x + 2.)
  end function unefonction_getvalue

  double precision function gaussienne_getvalue(self, x)
    class(gaussienne), intent(in) :: self
    double precision, intent(in) :: x

    :
    gaussienne_getvalue = norme * exp(-(x - moy)**2 / (2.d0 * self%sigma**2))

  end function gaussienne_getvalue

end module fonction


program main
  use rechercheRacine
  use fonction
  implicit none

  type(unefonction) :: fone
  type(gaussienne) :: fgauss

  :
  call newtonRaphson(racine, fone)
  call newtonRaphson(cible = cible, f = fgauss, racine = racine)

end program main

Segmentation error when passing a function as an argument in a subroutine

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