Date: 2022-08-09T09:05:51+00:00

Actual source code: ex16f90.F90
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> ./ex16f90 [-help] [-n <n>] [-m <m>] [SLEPc opts]
     11: !
     12: !  Description: Simple example that solves a quadratic eigensystem with the
     13: !  PEP object. This is the Fortran90 equivalent to ex16.c
     14: !
     15: !  The command line options are:
     16: !    -n <n>, where <n> = number of grid subdivisions in x dimension
     17: !    -m <m>, where <m> = number of grid subdivisions in y dimension
     18: !
     19: ! ----------------------------------------------------------------------
     20: !
     21:       program main
     22: #include <slepc/finclude/slepcpep.h>
     23:       use slepcpep
     24:       implicit none

     26: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     27: !     Declarations
     28: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     29: !
     30: !  Variables:
     31: !     M,C,K  problem matrices
     32: !     pep    polynomial eigenproblem solver context

     34:       Mat            M, C, K, A(3)
     35:       PEP            pep
     36:       PEPType        tname
     37:       PetscInt       N, nx, ny, i, j, Istart, Iend, II
     38:       PetscInt       nev, ithree
     39:       PetscMPIInt    rank
     40:       PetscErrorCode ierr
     41:       PetscBool      flg, terse
     42:       PetscScalar    mone, two, four, val

     44: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     45: !     Beginning of program
     46: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

     48:       call SlepcInitialize(PETSC_NULL_CHARACTER,ierr)
     49:       if (ierr .ne. 0) then
     50:         print*,'SlepcInitialize failed'
     51:         stop
     52:       endif
     53:       call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr);CHKERRA(ierr)
     54:       nx = 10
     55:       call PetscOptionsGetInt(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-n',nx,flg,ierr);CHKERRA(ierr)
     56:       call PetscOptionsGetInt(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-m',ny,flg,ierr);CHKERRA(ierr)
     57:       if (.not. flg) then
     58:         ny = nx
     59:       endif
     60:       N = nx*ny
     61:       if (rank .eq. 0) then
     62:         write(*,100) N, nx, ny
     63:       endif
     64:  100  format (/'Quadratic Eigenproblem, N=',I6,' (',I4,'x',I4,' grid)')

     66: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     67: !     Compute the matrices that define the eigensystem, (k^2*M+k*C+K)x=0
     68: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

     70: !     ** K is the 2-D Laplacian
     71:       call MatCreate(PETSC_COMM_WORLD,K,ierr);CHKERRA(ierr)
     72:       call MatSetSizes(K,PETSC_DECIDE,PETSC_DECIDE,N,N,ierr);CHKERRA(ierr)
     73:       call MatSetFromOptions(K,ierr);CHKERRA(ierr)
     74:       call MatSetUp(K,ierr);CHKERRA(ierr)
     75:       call MatGetOwnershipRange(K,Istart,Iend,ierr);CHKERRA(ierr)
     76:       mone = -1.0
     77:       four = 4.0
     78:       do II=Istart,Iend-1
     79:         i = II/nx
     80:         j = II-i*nx
     81:         if (i .gt. 0) then
     82:           call MatSetValue(K,II,II-nx,mone,INSERT_VALUES,ierr);CHKERRA(ierr)
     83:         endif
     84:         if (i .lt. ny-1) then
     85:           call MatSetValue(K,II,II+nx,mone,INSERT_VALUES,ierr);CHKERRA(ierr)
     86:         endif
     87:         if (j .gt. 0) then
     88:           call MatSetValue(K,II,II-1,mone,INSERT_VALUES,ierr);CHKERRA(ierr)
     89:         endif
     90:         if (j .lt. nx-1) then
     91:           call MatSetValue(K,II,II+1,mone,INSERT_VALUES,ierr);CHKERRA(ierr)
     92:         endif
     93:         call MatSetValue(K,II,II,four,INSERT_VALUES,ierr);CHKERRA(ierr)
     94:       end do
     95:       call MatAssemblyBegin(K,MAT_FINAL_ASSEMBLY,ierr);CHKERRA(ierr)
     96:       call MatAssemblyEnd(K,MAT_FINAL_ASSEMBLY,ierr);CHKERRA(ierr)

     98: !     ** C is the 1-D Laplacian on horizontal lines
     99:       call MatCreate(PETSC_COMM_WORLD,C,ierr);CHKERRA(ierr)
    100:       call MatSetSizes(C,PETSC_DECIDE,PETSC_DECIDE,N,N,ierr);CHKERRA(ierr)
    101:       call MatSetFromOptions(C,ierr);CHKERRA(ierr)
    102:       call MatSetUp(C,ierr);CHKERRA(ierr)
    103:       call MatGetOwnershipRange(C,Istart,Iend,ierr);CHKERRA(ierr)
    104:       two = 2.0
    105:       do II=Istart,Iend-1
    106:         i = II/nx
    107:         j = II-i*nx
    108:         if (j .gt. 0) then
    109:           call MatSetValue(C,II,II-1,mone,INSERT_VALUES,ierr);CHKERRA(ierr)
    110:         endif
    111:         if (j .lt. nx-1) then
    112:           call MatSetValue(C,II,II+1,mone,INSERT_VALUES,ierr);CHKERRA(ierr)
    113:         endif
    114:         call MatSetValue(C,II,II,two,INSERT_VALUES,ierr);CHKERRA(ierr)
    115:       end do
    116:       call MatAssemblyBegin(C,MAT_FINAL_ASSEMBLY,ierr);CHKERRA(ierr)
    117:       call MatAssemblyEnd(C,MAT_FINAL_ASSEMBLY,ierr);CHKERRA(ierr)

    119: !     ** M is a diagonal matrix
    120:       call MatCreate(PETSC_COMM_WORLD,M,ierr);CHKERRA(ierr)
    121:       call MatSetSizes(M,PETSC_DECIDE,PETSC_DECIDE,N,N,ierr);CHKERRA(ierr)
    122:       call MatSetFromOptions(M,ierr);CHKERRA(ierr)
    123:       call MatSetUp(M,ierr);CHKERRA(ierr)
    124:       call MatGetOwnershipRange(M,Istart,Iend,ierr);CHKERRA(ierr)
    125:       do II=Istart,Iend-1
    126:         val = II+1
    127:         call MatSetValue(M,II,II,val,INSERT_VALUES,ierr);CHKERRA(ierr)
    128:       end do
    129:       call MatAssemblyBegin(M,MAT_FINAL_ASSEMBLY,ierr);CHKERRA(ierr)
    130:       call MatAssemblyEnd(M,MAT_FINAL_ASSEMBLY,ierr);CHKERRA(ierr)

    132: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    133: !     Create the eigensolver and set various options
    134: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    136: !     ** Create eigensolver context
    137:       call PEPCreate(PETSC_COMM_WORLD,pep,ierr);CHKERRA(ierr)

    139: !     ** Set matrices and problem type
    140:       A(1) = K
    141:       A(2) = C
    142:       A(3) = M
    143:       ithree = 3
    144:       call PEPSetOperators(pep,ithree,A,ierr);CHKERRA(ierr)
    145:       call PEPSetProblemType(pep,PEP_GENERAL,ierr);CHKERRA(ierr)

    147: !     ** Set solver parameters at runtime
    148:       call PEPSetFromOptions(pep,ierr);CHKERRA(ierr)

    150: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    151: !     Solve the eigensystem
    152: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    154:       call PEPSolve(pep,ierr);CHKERRA(ierr)

    156: !     ** Optional: Get some information from the solver and display it
    157:       call PEPGetType(pep,tname,ierr);CHKERRA(ierr)
    158:       if (rank .eq. 0) then
    159:         write(*,120) tname
    160:       endif
    161:  120  format (' Solution method: ',A)
    162:       call PEPGetDimensions(pep,nev,PETSC_NULL_INTEGER,PETSC_NULL_INTEGER,ierr);CHKERRA(ierr)
    163:       if (rank .eq. 0) then
    164:         write(*,130) nev
    165:       endif
    166:  130  format (' Number of requested eigenvalues:',I4)

    168: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    169: !     Display solution and clean up
    170: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    172: !     ** show detailed info unless -terse option is given by user
    173:       call PetscOptionsHasName(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-terse',terse,ierr);CHKERRA(ierr)
    174:       if (terse) then
    175:         call PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_NULL_VIEWER,ierr);CHKERRA(ierr)
    176:       else
    177:         call PetscViewerPushFormat(PETSC_VIEWER_STDOUT_WORLD,PETSC_VIEWER_ASCII_INFO_DETAIL,ierr);CHKERRA(ierr)
    178:         call PEPConvergedReasonView(pep,PETSC_VIEWER_STDOUT_WORLD,ierr);CHKERRA(ierr)
    179:         call PEPErrorView(pep,PEP_ERROR_BACKWARD,PETSC_VIEWER_STDOUT_WORLD,ierr);CHKERRA(ierr)
    180:         call PetscViewerPopFormat(PETSC_VIEWER_STDOUT_WORLD,ierr);CHKERRA(ierr)
    181:       endif
    182:       call PEPDestroy(pep,ierr);CHKERRA(ierr)
    183:       call MatDestroy(K,ierr);CHKERRA(ierr)
    184:       call MatDestroy(C,ierr);CHKERRA(ierr)
    185:       call MatDestroy(M,ierr);CHKERRA(ierr)
    186:       call SlepcFinalize(ierr)
    187:       end

    189: !/*TEST
    190: !
    191: !   test:
    192: !      suffix: 1
    193: !      args: -pep_nev 4 -pep_ncv 19 -terse
    194: !      requires: !complex
    195: !
    196: !TEST*/