! D03PJF Example Program Text
! Mark 30.2 Release. NAG Copyright 2024.
Module d03pjfe_mod
! D03PJF Example Program Module:
! Parameters and User-defined Routines
! .. Use Statements ..
Use nag_library, Only: nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Accessibility Statements ..
Private
Public :: bndary, odedef, pdedef, uvinit
! .. Parameters ..
Real (Kind=nag_wp), Parameter :: one = 1.0_nag_wp
Integer, Parameter, Public :: itrace = 0, nin = 5, nout = 6, &
npde = 1, nv = 1, nxi = 1
Logical, Parameter, Public :: print_stat = .False.
! .. Local Scalars ..
Real (Kind=nag_wp), Public, Save :: ts
Contains
Subroutine uvinit(npde,npts,x,u,nv,v)
! Routine for PDE initial values (start time is 0.1D-6)
! .. Scalar Arguments ..
Integer, Intent (In) :: npde, npts, nv
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (Out) :: u(npde,npts), v(nv)
Real (Kind=nag_wp), Intent (In) :: x(npts)
! .. Local Scalars ..
Integer :: i
! .. Intrinsic Procedures ..
Intrinsic :: exp
! .. Executable Statements ..
v(1) = ts
Do i = 1, npts
u(1,i) = exp(ts*(one-x(i))) - one
End Do
Return
End Subroutine uvinit
Subroutine odedef(npde,t,nv,v,vdot,nxi,xi,ucp,ucpx,rcp,ucpt,ucptx,f, &
ires)
! .. Scalar Arguments ..
Real (Kind=nag_wp), Intent (In) :: t
Integer, Intent (Inout) :: ires
Integer, Intent (In) :: npde, nv, nxi
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (Out) :: f(nv)
Real (Kind=nag_wp), Intent (In) :: rcp(npde,nxi), ucp(npde,nxi), &
ucpt(npde,nxi), ucptx(npde,nxi), &
ucpx(npde,nxi), v(nv), vdot(nv), &
xi(nxi)
! .. Executable Statements ..
If (ires==1) Then
f(1) = vdot(1) - v(1)*ucp(1,1) - ucpx(1,1) - one - t
Else If (ires==-1) Then
f(1) = vdot(1)
End If
Return
End Subroutine odedef
Subroutine pdedef(npde,t,x,nptl,u,ux,nv,v,vdot,p,q,r,ires)
! .. Scalar Arguments ..
Real (Kind=nag_wp), Intent (In) :: t
Integer, Intent (Inout) :: ires
Integer, Intent (In) :: npde, nptl, nv
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (Out) :: p(npde,npde,nptl), q(npde,nptl), &
r(npde,nptl)
Real (Kind=nag_wp), Intent (In) :: u(npde,nptl), ux(npde,nptl), v(nv), &
vdot(nv), x(nptl)
! .. Local Scalars ..
Integer :: i
! .. Executable Statements ..
Do i = 1, nptl
p(1,1,i) = v(1)*v(1)
r(1,i) = ux(1,i)
q(1,i) = -x(i)*ux(1,i)*v(1)*vdot(1)
End Do
Return
End Subroutine pdedef
Subroutine bndary(npde,t,u,ux,nv,v,vdot,ibnd,beta,gamma,ires)
! .. Scalar Arguments ..
Real (Kind=nag_wp), Intent (In) :: t
Integer, Intent (In) :: ibnd, npde, nv
Integer, Intent (Inout) :: ires
! .. Array Arguments ..
Real (Kind=nag_wp), Intent (Out) :: beta(npde), gamma(npde)
Real (Kind=nag_wp), Intent (In) :: u(npde), ux(npde), v(nv), vdot(nv)
! .. Intrinsic Procedures ..
Intrinsic :: exp
! .. Executable Statements ..
beta(1) = 1.0E0_nag_wp
If (ibnd==0) Then
gamma(1) = -v(1)*exp(t)
Else
gamma(1) = -v(1)*vdot(1)
End If
Return
End Subroutine bndary
End Module d03pjfe_mod
Program d03pjfe
! D03PJF Example Main Program
! .. Use Statements ..
Use d03pjfe_mod, Only: bndary, itrace, nin, nout, npde, nv, nxi, odedef, &
pdedef, print_stat, ts, uvinit
Use nag_library, Only: d03pjf, nag_wp
! .. Implicit None Statement ..
Implicit None
! .. Local Scalars ..
Real (Kind=nag_wp) :: tout
Integer :: i, ifail, ind, it, itask, itol, &
latol, lenode, lisave, lrsave, &
lrtol, m, nbkpts, nel, neqn, np1, &
npoly, npts, nwkres
Logical :: theta
Character (1) :: laopt, norm
! .. Local Arrays ..
Real (Kind=nag_wp) :: algopt(30), xi(nxi)
Real (Kind=nag_wp), Allocatable :: atol(:), rsave(:), rtol(:), u(:), &
x(:), xbkpts(:)
Integer, Allocatable :: isave(:)
! .. Intrinsic Procedures ..
Intrinsic :: abs, mod, real
! .. Executable Statements ..
Write (nout,*) 'D03PJF Example Program Results'
! Skip heading in data file
Read (nin,*)
Read (nin,*) m, nbkpts, npoly
nel = nbkpts - 1
npts = nel*npoly + 1
neqn = npde*npts + nv
np1 = npoly + 1
nwkres = np1*(3*np1+npde*npde+6*npde+nbkpts+1)
nwkres = nwkres + 8*npde + nxi*(5*npde+1) + nv + 3
lenode = 11*neqn + 50
lisave = 25*neqn + 24
lrsave = neqn*neqn + neqn + nwkres + lenode
Allocate (u(neqn),rsave(lrsave),x(npts),xbkpts(nbkpts),isave(lisave))
Read (nin,*) itol
latol = 1
lrtol = 1
If (itol>2) Then
latol = neqn
End If
If (mod(itol,2)==0) Then
lrtol = neqn
End If
Allocate (atol(latol),rtol(lrtol))
Read (nin,*) atol(1:latol), rtol(1:lrtol)
Read (nin,*) ts
! Set break-points
Do i = 1, nbkpts
xbkpts(i) = real(i-1,kind=nag_wp)/real(nbkpts-1,kind=nag_wp)
End Do
Read (nin,*) xi(1:nxi)
Read (nin,*) norm, laopt
ind = 0
itask = 1
! Set theta to .TRUE. if the Theta integrator is required
theta = .False.
algopt(1:30) = 0.0_nag_wp
If (theta) Then
algopt(1) = 2.0_nag_wp
End If
Write (nout,99998)
Write (nout,99997) atol
Write (nout,99996) npoly
Write (nout,99995) nel
Write (nout,99994) npts
Write (nout,99999)
! Output value solution at t = 0.1*(2**k) for k=1,2,...,5
tout = 0.1_nag_wp
Do it = 1, 5
tout = tout + tout
! ifail: behaviour on error exit
! =0 for hard exit, =1 for quiet-soft, =-1 for noisy-soft
ifail = 0
Call d03pjf(npde,m,ts,tout,pdedef,bndary,u,nbkpts,xbkpts,npoly,npts,x, &
nv,odedef,nxi,xi,neqn,uvinit,rtol,atol,itol,norm,laopt,algopt,rsave, &
lrsave,isave,lisave,itask,itrace,ind,ifail)
If (abs(u(1))<10.0_nag_wp) Then
Write (nout,99993) ts, u(1)
Else
Write (nout,99992) ts, u(1)
End If
End Do
If (print_stat) Then
Write (nout,*)
Write (nout,99991) 'time steps', isave(1)
Write (nout,99991) 'function evaluations', isave(2)
Write (nout,99991) 'Jacobian evaluations', isave(3)
Write (nout,99991) 'iterations', isave(5)
End If
99999 Format (3X,'time',8X,'solution at x=0')
99998 Format (/,/,' Simple coupled PDE using BDF')
99997 Format (' Accuracy requirement = ',1P,E12.3)
99996 Format (' Degree of Polynomial = ',I4)
99995 Format (' Number of elements = ',I4)
99994 Format (' Number of mesh points = ',I4,/)
99993 Format (1X,F6.1,10X,F7.2)
99992 Format (1X,F6.1,10X,F6.1)
99991 Format (' Number of ',A20,' = ',I6)
End Program d03pjfe