Date: 2022-08-09T09:05:58+00:00

Actual source code: test3f.F
slepc-3.17.2 2022-08-09
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      1: !
      2: !  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      3: !  SLEPc - Scalable Library for Eigenvalue Problem Computations
      4: !  Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
      5: !
      6: !  This file is part of SLEPc.
      7: !  SLEPc is distributed under a 2-clause BSD license (see LICENSE).
      8: !  - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      9: !
     10: !  Program usage: mpiexec -n <np> ./test3f [-help] [-n <n>] [all SLEPc options]
     11: !
     12: !  Description: square root of the 2-D Laplacian.
     13: !
     14: !  The command line options are:
     15: !    -n <n>, where <n> = matrix rows and columns
     16: !
     17: ! ----------------------------------------------------------------------
     18: !
     19:       program main
     20: #include <slepc/finclude/slepcmfn.h>
     21:       use slepcmfn
     22:       implicit none

     24: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     25: !     Declarations
     26: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     27: !
     28:       Mat                A, B
     29:       MFN                mfn
     30:       FN                 f
     31:       MFNConvergedReason reason;
     32:       Vec                v, y
     33:       PetscInt           Nt, n, i, j, II
     34:       PetscInt           Istart, maxit, ncv
     35:       PetscInt           col, its, Iend
     36:       PetscScalar        val
     37:       PetscReal          tol, norm
     38:       PetscMPIInt        rank
     39:       PetscErrorCode     ierr
     40:       PetscBool          flg

     42: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     43: !     Beginning of program
     44: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

     46:       call SlepcInitialize(PETSC_NULL_CHARACTER,ierr)
     47:       call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)
     48:       n = 4
     49:       call PetscOptionsGetInt(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,  &
     50:      &                        '-n',n,flg,ierr)
     51:       Nt = n*n

     53:       if (rank .eq. 0) then
     54:         write(*,100) n
     55:       endif
     56:  100  format (/'nSquare root of Laplacian, n=',I3,' (Fortran)')

     58: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     59: !     Compute the discrete 2-D Laplacian
     60: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

     62:       call MatCreate(PETSC_COMM_WORLD,A,ierr)
     63:       call MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,Nt,Nt,ierr)
     64:       call MatSetFromOptions(A,ierr)
     65:       call MatSetUp(A,ierr)

     67:       call MatGetOwnershipRange(A,Istart,Iend,ierr)
     68:       do II=Istart,Iend-1
     69:         i = II/n
     70:         j = II-i*n
     71:         val = -1.0
     72:         if (i .gt. 0) then
     73:           col = II-n
     74:           call MatSetValue(A,II,col,val,INSERT_VALUES,ierr)
     75:         end if
     76:         if (i .lt. n-1) then
     77:           col = II+n
     78:           call MatSetValue(A,II,col,val,INSERT_VALUES,ierr)
     79:         end if
     80:         if (j .gt. 0) then
     81:           col = II-1
     82:           call MatSetValue(A,II,col,val,INSERT_VALUES,ierr)
     83:         end if
     84:         if (j .lt. n-1) then
     85:           col = II+1
     86:           call MatSetValue(A,II,col,val,INSERT_VALUES,ierr)
     87:         end if
     88:         val = 4.0
     89:         call MatSetValue(A,II,II,val,INSERT_VALUES,ierr)
     90:       enddo

     92:       call MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY,ierr)
     93:       call MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY,ierr)

     95:       call MatCreateVecs(A,PETSC_NULL_VEC,v,ierr)
     96:       i = 0
     97:       val = 1.0
     98:       call VecSetValue(v,i,val,INSERT_VALUES,ierr)
     99:       call VecAssemblyBegin(v,ierr)
    100:       call VecAssemblyEnd(v,ierr)
    101:       call VecDuplicate(v,y,ierr)

    103: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    104: !     Compute singular values
    105: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    107:       call MFNCreate(PETSC_COMM_WORLD,mfn,ierr)
    108:       call MFNSetOperator(mfn,A,ierr)
    109:       call MFNGetFN(mfn,f,ierr)
    110:       call FNSetType(f,FNSQRT,ierr)

    112: !     ** test some interface functions
    113:       call MFNGetOperator(mfn,B,ierr)
    114:       call MatView(B,PETSC_VIEWER_STDOUT_WORLD,ierr)
    115:       call MFNSetOptionsPrefix(mfn,'myprefix_',ierr)
    116:       tol = 1e-4
    117:       maxit = 500
    118:       call MFNSetTolerances(mfn,tol,maxit,ierr)
    119:       ncv = 6
    120:       call MFNSetDimensions(mfn,ncv,ierr)
    121:       call MFNSetErrorIfNotConverged(mfn,PETSC_TRUE,ierr)
    122:       call MFNSetFromOptions(mfn,ierr)

    124: !     ** query properties and print them
    125:       call MFNGetTolerances(mfn,tol,maxit,ierr)
    126:       if (rank .eq. 0) then
    127:         write(*,110) tol,maxit
    128:       endif
    129:  110  format (/' Tolerance: ',F7.4,', maxit: ',I4)
    130:       call MFNGetDimensions(mfn,ncv,ierr)
    131:       if (rank .eq. 0) then
    132:         write(*,120) ncv
    133:       endif
    134:  120  format (' Subspace dimension: ',I3)
    135:       call MFNGetErrorIfNotConverged(mfn,flg,ierr)
    136:       if (rank .eq. 0 .and. flg) then
    137:         write(*,*) 'Erroring out if convergence fails'
    138:       endif

    140: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    141: !     Call the solver
    142: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    144:       call MFNSolve(mfn,v,y,ierr)
    145:       call MFNGetConvergedReason(mfn,reason,ierr)
    146:       if (rank .eq. 0) then
    147:         write(*,130) reason
    148:       endif
    149:  130  format (' Converged reason:',I2)
    150:       call MFNGetIterationNumber(mfn,its,ierr)
    151: !     if (rank .eq. 0) then
    152: !       write(*,140) its
    153: !     endif
    154: !140  format (' Number of iterations of the method:',I4)

    156:       call VecNorm(y,NORM_2,norm,ierr)
    157:       if (rank .eq. 0) then
    158:         write(*,150) norm
    159:       endif
    160:  150  format (' sqrt(A)*v has norm ',F7.4)

    162:       call MFNDestroy(mfn,ierr)
    163:       call MatDestroy(A,ierr)
    164:       call VecDestroy(v,ierr)
    165:       call VecDestroy(y,ierr)

    167:       call SlepcFinalize(ierr)
    168:       end

    170: !/*TEST
    171: !
    172: !   test:
    173: !      suffix: 1
    174: !      args: -log_exclude mfn
    175: !
    176: !TEST*/