! C05PBF Example Program Text ! Mark 24 Release. NAG Copyright 2012. Module c05pbfe_mod ! C05PBF Example Program Module: ! Parameters and User-defined Routines ! .. Use Statements .. Use nag_library, Only: nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Real (Kind=nag_wp), Parameter :: one = 1.0_nag_wp Real (Kind=nag_wp), Parameter :: three = 3.0_nag_wp Real (Kind=nag_wp), Parameter :: two = 2.0_nag_wp Integer, Parameter :: n = 9, nout = 6 Integer, Parameter :: ldfjac = n Contains Subroutine fcn(n,x,fvec,fjac,ldfjac,iflag) ! .. Scalar Arguments .. Integer, Intent (Inout) :: iflag Integer, Intent (In) :: ldfjac, n ! .. Array Arguments .. Real (Kind=nag_wp), Intent (Inout) :: fjac(ldfjac,n), fvec(n) Real (Kind=nag_wp), Intent (In) :: x(n) ! .. Local Scalars .. Integer :: k ! .. Executable Statements .. If (iflag/=2) Then fvec(1:n) = (three-two*x(1:n))*x(1:n) + one fvec(2:n) = fvec(2:n) - x(1:(n-1)) fvec(1:(n-1)) = fvec(1:(n-1)) - two*x(2:n) Else fjac(1:n,1:n) = 0.0_nag_wp fjac(1,1) = three - two*two*x(1) fjac(1,2) = -two Do k = 2, n - 1 fjac(k,k) = three - two*two*x(k) fjac(k,k-1) = -one fjac(k,k+1) = -two End Do fjac(n,n-1) = -one fjac(n,n) = three - two*two*x(n) End If Return End Subroutine fcn End Module c05pbfe_mod Program c05pbfe ! C05PBF Example Main Program ! .. Use Statements .. Use nag_library, Only: c05pbf, dnrm2, nag_wp, x02ajf Use c05pbfe_mod, Only: fcn, ldfjac, n, nout, one ! .. Implicit None Statement .. Implicit None ! .. Local Scalars .. Real (Kind=nag_wp) :: fnorm, xtol Integer :: ifail, j, lwa ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: fjac(:,:), fvec(:), x(:) Real (Kind=nag_wp) :: wa(1) ! .. Intrinsic Procedures .. Intrinsic :: sqrt ! .. Executable Statements .. Write (nout,*) 'C05PBF Example Program Results' Allocate (fjac(ldfjac,n),fvec(n),x(n)) ! The following starting values provide a rough solution. x(1:n) = -one xtol = sqrt(x02ajf()) ifail = -1 Call c05pbf(fcn,n,x,fvec,fjac,ldfjac,xtol,wa,lwa,ifail) Select Case (ifail) Case (0) ! The NAG name equivalent of dnrm2 is f06ejf fnorm = dnrm2(n,fvec,1) Write (nout,*) Write (nout,99999) 'Final 2-norm of the residuals =', fnorm Write (nout,*) Write (nout,*) 'Final approximate solution' Write (nout,*) Write (nout,99998)(x(j),j=1,n) Case (2:) Write (nout,*) Write (nout,*) 'Approximate solution' Write (nout,*) Write (nout,99998)(x(j),j=1,n) End Select 99999 Format (1X,A,E12.4) 99998 Format (1X,3F12.4) End Program c05pbfe