! F12ARF Example Program Text ! Mark 24 Release. NAG Copyright 2012. Module f12arfe_mod ! F12ARF Example Program Module: ! Parameters and User-defined Routines ! .. Use Statements .. Use nag_library, Only: nag_wp ! .. Implicit None Statement .. Implicit None ! .. Parameters .. Complex (Kind=nag_wp), Parameter :: four = (4.0_nag_wp,0.0_nag_wp) Complex (Kind=nag_wp), Parameter :: one = (1.0_nag_wp,0.0_nag_wp) Complex (Kind=nag_wp), Parameter :: six = (6.0_nag_wp,0.0_nag_wp) Complex (Kind=nag_wp), Parameter :: two = (2.0_nag_wp,0.0_nag_wp) Integer, Parameter :: imon = 0, licomm = 140, & nerr = 6, nin = 5, nout = 6 Contains Subroutine mv(nx,v,w) ! Compute the out-of--place matrix vector multiplication Y<---M*X, ! where M is mass matrix formed by using piecewise linear elements ! on [0,1]. ! .. Use Statements .. Use nag_library, Only: zscal ! .. Scalar Arguments .. Integer, Intent (In) :: nx ! .. Array Arguments .. Complex (Kind=nag_wp), Intent (In) :: v(nx*nx) Complex (Kind=nag_wp), Intent (Out) :: w(nx*nx) ! .. Local Scalars .. Complex (Kind=nag_wp) :: h Integer :: j, n ! .. Intrinsic Procedures .. Intrinsic :: cmplx ! .. Executable Statements .. n = nx*nx w(1) = (four*v(1)+v(2))/six Do j = 2, n - 1 w(j) = (v(j-1)+four*v(j)+v(j+1))/six End Do w(n) = (v(n-1)+four*v(n))/six h = one/cmplx(n+1,kind=nag_wp) ! The NAG name equivalent of zscal is f06gdf Call zscal(n,h,w,1) Return End Subroutine mv End Module f12arfe_mod Program f12arfe ! F12ARF Example Main Program ! .. Use Statements .. Use nag_library, Only: dznrm2, f12anf, f12apf, f12aqf, f12arf, f12asf, & nag_wp, zgttrf, zgttrs Use f12arfe_mod, Only: four, imon, licomm, mv, nerr, nin, nout, one, & six, two ! .. Implicit None Statement .. Implicit None ! .. Local Scalars .. Complex (Kind=nag_wp) :: h, rho, s, s1, s2, s3, sigma Integer :: ifail, ifail1, info, irevcm, j, & lcomm, ldv, n, nconv, ncv, nev, & niter, nshift, nx ! .. Local Arrays .. Complex (Kind=nag_wp), Allocatable :: ax(:), comm(:), d(:,:), dd(:), & dl(:), du(:), du2(:), mx(:), & resid(:), v(:,:), x(:) Integer :: icomm(licomm) Integer, Allocatable :: ipiv(:) ! .. Intrinsic Procedures .. Intrinsic :: cmplx ! .. Executable Statements .. Write (nout,*) 'F12ARF Example Program Results' Write (nout,*) ! Skip heading in data file Read (nin,*) Read (nin,*) nx, nev, ncv n = nx*nx lcomm = 3*n + 3*ncv*ncv + 5*ncv + 60 ldv = n Allocate (comm(lcomm),ax(n),d(ncv,2),dd(n),dl(n),du(n),du2(n),mx(n), & resid(n),v(ldv,ncv),x(n),ipiv(n)) ifail = 0 Call f12anf(n,nev,ncv,icomm,licomm,comm,lcomm,ifail) ! Set the mode. ifail = 0 Call f12arf('SHIFTED INVERSE',icomm,comm,ifail) ! Set problem type. Call f12arf('GENERALIZED',icomm,comm,ifail) sigma = (500.0_nag_wp,0.0_nag_wp) rho = (10.0_nag_wp,0.0_nag_wp) h = one/cmplx(n+1,kind=nag_wp) s = rho/two s1 = -one/h - s - sigma*h/six s2 = two/h - four*sigma*h/six s3 = -one/h + s - sigma*h/six dl(1:n-1) = s1 dd(1:n-1) = s2 du(1:n-1) = s3 dd(n) = s2 ! The NAG name equivalent of zgttrf is f07crf Call zgttrf(n,dl,dd,du,du2,ipiv,info) If (info/=0) Then Write (nerr,99999) info Go To 100 End If irevcm = 0 ifail = -1 revcm: Do Call f12apf(irevcm,resid,v,ldv,x,mx,nshift,comm,icomm,ifail) If (irevcm==5) Then Exit revcm Else If (irevcm==-1) Then ! Perform x <--- OP*x = inv[A-SIGMA*M]*M*x Call mv(nx,x,ax) x(1:n) = ax(1:n) ! The NAG name equivalent of zgttrs is f07csf Call zgttrs('N',n,1,dl,dd,du,du2,ipiv,x,n,info) If (info/=0) Then Write (nerr,99998) info Exit revcm End If Else If (irevcm==1) Then ! Perform x <--- OP*x = inv[A-SIGMA*M]*M*x, ! MX stored in COMM from location IPNTR(3) ! The NAG name equivalent of zgttrs is f07csf Call zgttrs('N',n,1,dl,dd,du,du2,ipiv,mx,n,info) x(1:n) = mx(1:n) If (info/=0) Then Write (nerr,99998) info Exit revcm End If Else If (irevcm==2) Then ! Perform y <--- M*x Call mv(nx,x,ax) x(1:n) = ax(1:n) Else If (irevcm==4 .And. imon/=0) Then ! Output monitoring information Call f12asf(niter,nconv,d,d(1,2),icomm,comm) ! The NAG name equivalent of dznrm2 is f06jjf Write (6,99997) niter, nconv, dznrm2(nev,d(1,2),1) End If End Do revcm If (ifail==0 .And. info==0) Then ! Post-Process using F12AQF to compute eigenvalues/vectors. ifail1 = 0 Call f12aqf(nconv,d,v,ldv,sigma,resid,v,ldv,comm,icomm,ifail1) Write (nout,99996) nconv, sigma Write (nout,99995)(j,d(j,1),j=1,nconv) End If 100 Continue 99999 Format (1X,'** Error status returned by ZGTTRF, INFO =',I12) 99998 Format (1X,'** Error status returned by ZGTTRS, INFO =',I12) 99997 Format (1X,'Iteration',1X,I3,', No. converged =',1X,I3,', norm o', & 'f estimates =',E16.8) 99996 Format (1X/' The ',I4,' generalized Ritz values closest to (',F7.3,',', & F7.3,') are:'/) 99995 Format (1X,I8,5X,'( ',F10.4,' , ',F10.4,' )') End Program f12arfe