!   E04JCF Example Program Text
!   Mark 23 Release. NAG Copyright 2011.
    MODULE e04jcfe_mod

!      E04JCF Example Program Module:
!             Parameters and User-defined Routines

!      .. Use Statements ..
       USE nag_library, ONLY : nag_wp
!      .. Implicit None Statement ..
       IMPLICIT NONE
!      .. Parameters ..
       INTEGER, PARAMETER                  :: nout = 6
    CONTAINS
       SUBROUTINE objfun(n,x,f,iuser,ruser,inform)

!         .. Implicit None Statement ..
          IMPLICIT NONE
!         .. Parameters ..
          REAL (KIND=nag_wp), PARAMETER       :: five = 5.0_nag_wp
          REAL (KIND=nag_wp), PARAMETER       :: ten = 1.0E1_nag_wp
          REAL (KIND=nag_wp), PARAMETER       :: two = 2.0_nag_wp
!         .. Scalar Arguments ..
          REAL (KIND=nag_wp), INTENT (OUT)    :: f
          INTEGER, INTENT (OUT)               :: inform
          INTEGER, INTENT (IN)                :: n
!         .. Array Arguments ..
          REAL (KIND=nag_wp), INTENT (INOUT)  :: ruser(*)
          REAL (KIND=nag_wp), INTENT (IN)     :: x(n)
          INTEGER, INTENT (INOUT)             :: iuser(*)
!         .. Executable Statements ..
          inform = 0

          f = (x(1)+ten*x(2))**2 + five*(x(3)-x(4))**2 + (x(2)-two*x(3))**4 + &
             ten*(x(1)-x(4))**4

          RETURN

       END SUBROUTINE objfun
       SUBROUTINE monfun(n,nf,x,f,rho,iuser,ruser,inform)

!         .. Implicit None Statement ..
          IMPLICIT NONE
!         .. Scalar Arguments ..
          REAL (KIND=nag_wp), INTENT (IN)     :: f, rho
          INTEGER, INTENT (OUT)               :: inform
          INTEGER, INTENT (IN)                :: n, nf
!         .. Array Arguments ..
          REAL (KIND=nag_wp), INTENT (INOUT)  :: ruser(*)
          REAL (KIND=nag_wp), INTENT (IN)     :: x(n)
          INTEGER, INTENT (INOUT)             :: iuser(*)
!         .. Executable Statements ..
          inform = 0

          WRITE (nout,FMT='(/4X,A,1P,E13.5,A,I16)') 'New RHO =', rho, &
             ', number of function evaluations =', nf
          WRITE (nout,FMT='(4X,A,1P,E13.5)') 'Current function value =', f
          WRITE (nout,FMT='(4X,A,/(4X,5E13.5))') 'The corresponding X is:', &
             x(1:n)

          RETURN

       END SUBROUTINE monfun
    END MODULE e04jcfe_mod
    PROGRAM e04jcfe

!      Example problem for E04JCF.

!      .. Use Statements ..
       USE nag_library, ONLY : e04jcf, e04jcp, nag_wp, x02alf
       USE e04jcfe_mod, ONLY : nout, objfun
!      .. Implicit None Statement ..
       IMPLICIT NONE
!      .. Local Scalars ..
       REAL (KIND=nag_wp)                  :: f, infbnd, rhobeg, rhoend
       INTEGER                             :: ifail, maxcal, n, nf, npt
!      .. Local Arrays ..
       REAL (KIND=nag_wp), ALLOCATABLE     :: bl(:), bu(:), x(:)
       REAL (KIND=nag_wp)                  :: ruser(1)
       INTEGER                             :: iuser(1)
!      .. Executable Statements ..
       WRITE (nout,*) 'E04JCF Example Program Results'

       maxcal = 500
       rhobeg = 1.0E-1_nag_wp
       rhoend = 1.0E-6_nag_wp
       n = 4
       npt = 2*n + 1

!      x(3) is unconstrained, so we're going to set bl(3) to a large
!      negative number and bu(3) to a large positive number.

       infbnd = x02alf()**0.25_nag_wp

       ALLOCATE (bl(n),bu(n),x(n))

       bl(1:n) = (/ 1.0_nag_wp, -2.0_nag_wp, -infbnd, 1.0_nag_wp/)
       bu(1:n) = (/ 3.0_nag_wp, 0.0_nag_wp, infbnd, 3.0_nag_wp/)
       x(1:n) = (/ 3.0_nag_wp, -1.0_nag_wp, 0.0_nag_wp, 1.0_nag_wp/)

!      USE monfun from e04jcfe_mod and pass this to e04jcf instead
!      of e04jcp to enable monitoring output

       ifail = -1
       CALL e04jcf(objfun,n,npt,x,bl,bu,rhobeg,rhoend,e04jcp,maxcal,f,nf, &
          iuser,ruser,ifail)

       SELECT CASE (ifail)
       CASE (0,2:5)

          IF (ifail==0) THEN
             WRITE (nout,FMT='(2(/1X,A),1P,E13.5)') &
                'Successful exit from E04JCF.', &
                'Function value at lowest point found =', f
          ELSE
             WRITE (nout,FMT='(/1X,A,1P,E13.5)') &
                'On exit from E04JCF, function value at lowest point found =', &
                f
          END IF

          WRITE (nout,FMT='(1X,A,/(2X,5E13.5))') 'The corresponding X is:', &
             x(1:n)
       END SELECT

    END PROGRAM e04jcfe