! C05QBF Example Program Text ! Mark 23 Release. NAG Copyright 2011. MODULE c05qbfe_mod ! C05QBF Example Program Module: ! Parameters and User-defined Routines ! .. Use Statements .. USE nag_library, ONLY : nag_wp ! .. Implicit None Statement .. IMPLICIT NONE ! .. Parameters .. INTEGER, PARAMETER :: n = 9, nout = 6 CONTAINS SUBROUTINE fcn(n,x,fvec,iuser,ruser,iflag) ! .. Implicit None Statement .. IMPLICIT NONE ! .. Scalar Arguments .. 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(*) ! .. Executable Statements .. fvec(1:n) = (3.0_nag_wp-2.0_nag_wp*x(1:n))*x(1:n) + 1.0_nag_wp fvec(2:n) = fvec(2:n) - x(1:(n-1)) fvec(1:(n-1)) = fvec(1:(n-1)) - 2.0_nag_wp*x(2:n) RETURN END SUBROUTINE fcn END MODULE c05qbfe_mod PROGRAM c05qbfe ! C05QBF Example Main Program ! .. Use Statements .. USE nag_library, ONLY : c05qbf, dnrm2, nag_wp, x02ajf USE c05qbfe_mod, ONLY : fcn, n, nout ! .. Implicit None Statement .. IMPLICIT NONE ! .. Local Scalars .. REAL (KIND=nag_wp) :: fnorm, xtol INTEGER :: i, ifail, j ! .. Local Arrays .. REAL (KIND=nag_wp), ALLOCATABLE :: fvec(:), x(:) REAL (KIND=nag_wp) :: ruser(1) INTEGER :: iuser(1) ! .. Intrinsic Functions .. INTRINSIC sqrt ! .. Executable Statements .. WRITE (nout,*) 'C05QBF Example Program Results' ALLOCATE (fvec(n),x(n)) ! The following starting values provide a rough solution. x(1:n) = -1.0E0_nag_wp xtol = sqrt(x02ajf()) ifail = -1 CALL c05qbf(fcn,n,x,fvec,xtol,iuser,ruser,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 (2:4) WRITE (nout,*) WRITE (nout,*) 'Approximate solution' WRITE (nout,*) WRITE (nout,99998) (x(i),i=1,n) END SELECT 99999 FORMAT (1X,A,E12.4) 99998 FORMAT (1X,3F12.4) END PROGRAM c05qbfe