! F12FCF Example Program Text ! Mark 24 Release. NAG Copyright 2012. Module f12fcfe_mod ! F12FCF 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 :: four = 4.0_nag_wp Real (Kind=nag_wp), Parameter :: one = 1.0_nag_wp Real (Kind=nag_wp), Parameter :: six = 6.0_nag_wp Real (Kind=nag_wp), Parameter :: two = 2.0_nag_wp Real (Kind=nag_wp), Parameter :: zero = 0.0_nag_wp Integer, Parameter :: imon = 0, licomm = 140, nin = 5, & nout = 6 Contains Subroutine mv(n,v,w) ! .. Use Statements .. Use nag_library, Only: dscal ! .. Scalar Arguments .. Integer, Intent (In) :: n ! .. Array Arguments .. Real (Kind=nag_wp), Intent (In) :: v(n) Real (Kind=nag_wp), Intent (Out) :: w(n) ! .. Local Scalars .. Real (Kind=nag_wp) :: h Integer :: j ! .. Intrinsic Procedures .. Intrinsic :: real ! .. Executable Statements .. h = one/(real(n+1,kind=nag_wp)*six) w(1) = four*v(1) + v(2) Do j = 2, n - 1 w(j) = v(j-1) + four*v(j) + v(j+1) End Do j = n w(j) = v(j-1) + four*v(j) ! The NAG name equivalent of dscal is f06edf Call dscal(n,h,w,1) Return End Subroutine mv Subroutine av(n,v,w) ! .. Use Statements .. Use nag_library, Only: dscal ! .. Scalar Arguments .. Integer, Intent (In) :: n ! .. Array Arguments .. Real (Kind=nag_wp), Intent (In) :: v(n) Real (Kind=nag_wp), Intent (Out) :: w(n) ! .. Local Scalars .. Real (Kind=nag_wp) :: h Integer :: j ! .. Intrinsic Procedures .. Intrinsic :: real ! .. Executable Statements .. h = one/real(n+1,kind=nag_wp) w(1) = two*v(1) - v(2) Do j = 2, n - 1 w(j) = -v(j-1) + two*v(j) - v(j+1) End Do j = n w(j) = -v(j-1) + two*v(j) ! The NAG name equivalent of dscal is f06edf Call dscal(n,one/h,w,1) Return End Subroutine av End Module f12fcfe_mod Program f12fcfe ! F12FCF Example Main Program ! .. Use Statements .. Use nag_library, Only: dgttrf, dgttrs, dnrm2, f12faf, f12fbf, f12fcf, & f12fdf, f12fef, nag_wp Use f12fcfe_mod, Only: av, four, imon, licomm, mv, nin, nout, one, six, & zero ! .. Implicit None Statement .. Implicit None ! .. Local Scalars .. Real (Kind=nag_wp) :: h, r1, r2, sigma Integer :: ifail, info, irevcm, j, lcomm, & ldv, n, nconv, ncv, nev, niter, & nshift ! .. Local Arrays .. Real (Kind=nag_wp), Allocatable :: ad(:), adl(:), adu(:), adu2(:), & comm(:), d(:,:), mx(:), & resid(:), v(:,:), x(:) Integer :: icomm(licomm) Integer, Allocatable :: ipiv(:) ! .. Intrinsic Procedures .. Intrinsic :: real ! .. Executable Statements .. Write (nout,*) 'F12FCF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) n, nev, ncv lcomm = 3*n + ncv*ncv + 8*ncv + 60 ldv = n Allocate (ad(n),adl(n),adu(n),adu2(n),comm(lcomm),d(ncv,2),mx(n), & resid(n),v(ldv,ncv),x(n),ipiv(n)) ifail = 0 Call f12faf(n,nev,ncv,icomm,licomm,comm,lcomm,ifail) ! We are solving a generalized problem ifail = 0 Call f12fdf('GENERALIZED',icomm,comm,ifail) h = one/real(n+1,kind=nag_wp) r1 = (four/six)*h r2 = (one/six)*h ad(1:n) = r1 adl(1:n) = r2 adu(1:n) = adl(1:n) ! The NAG name equivalent of dgttrf is f07cdf Call dgttrf(n,adl,ad,adu,adu2,ipiv,info) irevcm = 0 ifail = -1 revcm: Do Call f12fbf(irevcm,resid,v,ldv,x,mx,nshift,comm,icomm,ifail) If (irevcm==5) Then Exit revcm Else If (irevcm==-1 .Or. irevcm==1) Then ! Perform X <--- OP*x = inv[M]*A*x. Call av(n,x,mx) x(1:n) = mx(1:n) ! The NAG name equivalent of dgttrs is f07cef Call dgttrs('N',n,1,adl,ad,adu,adu2,ipiv,x,n,info) Else If (irevcm==2) Then ! Perform MX <--- M*x. Call mv(n,x,mx) Else If (irevcm==4 .And. imon/=0) Then ! Output monitoring information Call f12fef(niter,nconv,d,d(1,2),icomm,comm) ! The NAG name equivalent of dnrm2 is f06ejf Write (6,99999) niter, nconv, dnrm2(nev,d(1,2),1) End If End Do revcm If (ifail==0) Then ! Post-Process using F12FCF to compute eigenvalues/vectors. sigma = zero ifail = 0 Call f12fcf(nconv,d,v,ldv,sigma,resid,v,ldv,comm,icomm,ifail) Write (nout,99998) nconv Write (nout,99997)(j,d(j,1),j=1,nconv) End If 99999 Format (1X,'Iteration',1X,I3,', No. converged =',1X,I3,', norm o', & 'f estimates =',E16.8) 99998 Format (1X/' The ',I4,' generalized Ritz values of largest magn', & 'itude are:'/) 99997 Format (1X,I8,5X,F9.1) End Program f12fcfe