! C05QB_P0W_F Example Program Text
! Mark 30.2 Release. NAG Copyright 2024.
Module c05qb_p0w_fe_mod
! C05QB_P0W_F Example Program Module:
! Parameters and User-defined Routines
! .. Use Statements ..
Use iso_c_binding, Only: c_ptr
Use nag_library, Only: nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Accessibility Statements ..
Private
Public :: fcn
! .. Parameters ..
Integer, Parameter, Public :: n = 7, nout = 6
Contains
Subroutine fcn(ad_handle,n,x,fvec,iuser,ruser,iflag)
! .. Scalar Arguments ..
Type (c_ptr), Intent (Inout) :: ad_handle
Integer, Intent (Inout) :: iflag
Integer, Intent (In) :: n
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (Out) :: fvec(n)
Real (Kind=nag_wp), Intent (Inout) :: ruser(*)
Real (Kind=nag_wp), Intent (In) :: x(n)
Integer, Intent (Inout) :: iuser(*)
! .. Local Scalars ..
Integer :: i
! .. Executable Statements ..
Do i = 1, n
fvec(i) = (ruser(2)+ruser(3)*x(i))*x(i) - ruser(5)
End Do
Do i = 2, n
fvec(i) = fvec(i) + ruser(1)*x(i-1)
End Do
Do i = 1, n - 1
fvec(i) = fvec(i) + ruser(4)*x(i+1)
End Do
! Set iflag negative to terminate execution for any reason.
iflag = 0
Return
End Subroutine fcn
End Module c05qb_p0w_fe_mod
Program c05qb_p0w_fe
! C05QB_P0W_F Example Main Program
! .. Use Statements ..
Use c05qb_p0w_fe_mod, Only: fcn, n, nout
Use iso_c_binding, Only: c_ptr
Use nagad_library, Only: c05qb_p0w_f
Use nag_library, Only: nag_wp, x02ajf
! .. Implicit None Statement ..
Implicit None
! .. Local Scalars ..
Type (c_ptr) :: ad_handle
Real (Kind=nag_wp) :: xtol
Integer :: i, ifail
! .. Local Arrays ..
Real (Kind=nag_wp), Allocatable :: fvec(:), x(:)
Real (Kind=nag_wp) :: ruser(5)
Integer :: iuser(1)
! .. Intrinsic Procedures ..
Intrinsic :: sqrt
! .. Executable Statements ..
Write (nout,*) 'C05QB_P0W_F Example Program Results'
Allocate (fvec(n),x(n))
! The following starting values provide a rough solution.
x(1:n) = -1.0_nag_wp
ruser(1) = -1.0_nag_wp
ruser(2) = 3.0_nag_wp
ruser(3) = -2.0_nag_wp
ruser(4) = -2.0_nag_wp
ruser(5) = -1.0_nag_wp
xtol = sqrt(x02ajf())
ifail = 0
Call c05qb_p0w_f(ad_handle,fcn,n,x,fvec,xtol,iuser,ruser,ifail)
Write (nout,*) 'Final approximate solution'
Write (nout,99999)(x(i),i=1,n)
99999 Format (1X,3F12.4)
End Program c05qb_p0w_fe