! D01FDF Example Program Text ! Mark 24 Release. NAG Copyright 2012. Module d01fdfe_mod ! D01FDF 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 Function f(ndim,x) ! .. Function Return Value .. Real (Kind=nag_wp) :: f ! .. Scalar Arguments .. Integer, Intent (In) :: ndim ! .. Array Arguments .. Real (Kind=nag_wp), Intent (In) :: x(ndim) ! .. Intrinsic Procedures .. Intrinsic :: abs, sqrt, sum ! .. Executable Statements .. f = 1.0E0_nag_wp/sqrt(abs(2.25E0_nag_wp-sum(x(1:ndim)**2))) Return End Function f Subroutine region(ndim,x,j,c,d) ! .. Scalar Arguments .. Real (Kind=nag_wp), Intent (Out) :: c, d Integer, Intent (In) :: j, ndim ! .. Array Arguments .. Real (Kind=nag_wp), Intent (In) :: x(ndim) ! .. Intrinsic Procedures .. Intrinsic :: abs, sqrt, sum ! .. Executable Statements .. If (j>1) Then d = sqrt(abs(2.25E0_nag_wp-sum(x(1:(j-1))**2))) c = -d Else c = -1.5E0_nag_wp d = 1.5E0_nag_wp End If Return End Subroutine region End Module d01fdfe_mod Program d01fdfe ! D01FDF Example Main Program ! .. Use Statements .. Use nag_library, Only: d01fdf, d01fdv, nag_wp Use d01fdfe_mod, Only: f, nout, region ! .. Implicit None Statement .. Implicit None ! .. Local Scalars .. Real (Kind=nag_wp) :: r0, result, sigma, u Integer :: ifail, limit, ncalls, ndim ! .. Executable Statements .. Write (nout,*) 'D01FDF Example Program Results' ndim = 3 limit = 8000 u = 1.5E0_nag_wp sigma = 1.5E0_nag_wp r0 = 0.9E0_nag_wp ifail = 0 Call d01fdf(ndim,f,sigma,d01fdv,limit,r0,u,result,ncalls,ifail) Write (nout,*) Write (nout,*) 'Sphere-to-sphere transformation' Write (nout,*) Write (nout,99999) 'Estimated value of the integral = ', result Write (nout,99998) 'Number of integrand evaluations = ', ncalls Write (nout,*) Write (nout,*) 'Product region transformation' sigma = -1.0E0_nag_wp r0 = 0.8E0_nag_wp ifail = 0 Call d01fdf(ndim,f,sigma,region,limit,r0,u,result,ncalls,ifail) Write (nout,*) Write (nout,99999) 'Estimated value of the integral = ', result Write (nout,99998) 'Number of integrand evaluations = ', ncalls 99999 Format (1X,A,F9.3) 99998 Format (1X,A,I5) End Program d01fdfe