! D02PEF Example Program Text ! Mark 24 Release. NAG Copyright 2012. Module d02pefe_mod ! D02PEF 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 :: tol0 = 1.0E-3_nag_wp Integer, Parameter :: liwsav = 130, n = 2, nin = 5, & nout = 6, npts = 8 Integer, Parameter :: lrwsav = 350 + 32*n Contains Subroutine f(t,n,y,yp,iuser,ruser) ! .. Scalar Arguments .. Real (Kind=nag_wp), Intent (In) :: t Integer, Intent (In) :: n ! .. Array Arguments .. Real (Kind=nag_wp), Intent (Inout) :: ruser(*) Real (Kind=nag_wp), Intent (In) :: y(n) Real (Kind=nag_wp), Intent (Out) :: yp(n) Integer, Intent (Inout) :: iuser(*) ! .. Executable Statements .. yp(1) = y(2) yp(2) = -y(1) Return End Subroutine f End Module d02pefe_mod Program d02pefe ! D02PEF Example Main Program ! .. Use Statements .. Use nag_library, Only: d02pef, d02pqf, d02ptf, nag_wp Use d02pefe_mod, Only: f, liwsav, lrwsav, n, nin, nout, npts, tol0 ! .. Implicit None Statement .. Implicit None ! .. Local Scalars .. Real (Kind=nag_wp) :: hnext, hstart, tend, tgot, tinc, & tol, tstart, twant, waste Integer :: fevals, i, ifail, j, method, & stepcost, stepsok ! .. Local Arrays .. Real (Kind=nag_wp) :: ruser(1), thresh(n), ygot(n), & yinit(n), ymax(n), ypgot(n) Real (Kind=nag_wp), Allocatable :: rwsav(:) Integer :: iuser(1) Integer, Allocatable :: iwsav(:) ! .. Intrinsic Procedures .. Intrinsic :: real ! .. Executable Statements .. Write (nout,*) 'D02PEF Example Program Results' Allocate (iwsav(liwsav),rwsav(lrwsav)) ! Set initial conditions and input for D02PQF ! Skip heading in data file Read (nin,*) Read (nin,*) method Read (nin,*) tstart, tend Read (nin,*) yinit(1:n) Read (nin,*) hstart Read (nin,*) thresh(1:n) ! Set control for output tinc = (tend-tstart)/real(npts,kind=nag_wp) tol = 10.0_nag_wp*tol0 loop: Do i = 1, 2 tol = tol*0.1_nag_wp ! ifail: behaviour on error exit ! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft ifail = 0 Call d02pqf(n,tstart,tend,yinit,tol,thresh,method,hstart,iwsav,rwsav, & ifail) Write (nout,99999) tol Write (nout,99998) Write (nout,99997) tstart, yinit(1:n) twant = tstart Do j = 1, npts twant = twant + tinc ifail = 0 Call d02pef(f,n,twant,tgot,ygot,ypgot,ymax,iuser,ruser,iwsav,rwsav, & ifail) Write (nout,99997) tgot, ygot(1:n) End Do ifail = 0 Call d02ptf(fevals,stepcost,waste,stepsok,hnext,iwsav,rwsav,ifail) Write (nout,99996) fevals End Do loop 99999 Format (/' Calculation with TOL = ',1P,E8.1) 99998 Format (/' t y1 y2'/) 99997 Format (1X,F6.3,2(3X,F7.3)) 99996 Format (/' Cost of the integration in evaluations of F is',I6) End Program d02pefe