Date: 2013-07-02T14:40:20+00:00

Actual source code: ex1f.F
petsc-3.4.2 2013-07-02

      1: !
      2: !
      3: !/*T
      4: !   Concepts: vectors^basic routines
      5: !   Processors: n
      6: !T*/
      7: !
      8: ! -----------------------------------------------------------------------

     10:       program main
     11:       implicit none

     13: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     14: !                    Include files
     15: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     16: !
     17: !  The following include statements are required for Fortran programs
     18: !  that use PETSc vectors:
     19: !     petscsys.h       - base PETSc routines
     20: !     petscvec.h    - vectors
     21: !  Additional include statements may be needed if using additional
     22: !  PETSc routines in a Fortran program, e.g.,
     23: !     petscviewer.h - viewers
     24: !     petscis.h     - index sets
     25: !
     26: #include <finclude/petscsys.h>
     27: #include <finclude/petscvec.h>

     29: !
     30: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     31: !                   Variable declarations
     32: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     33: !
     34: !  Variables:
     35: !     x, y, w - vectors
     36: !     z       - array of vectors

     38:       Vec              x,y,w,z(5)
     39:       PetscReal        norm,v,v1,v2
     40:       PetscInt           n,ithree
     41:       PetscBool  flg
     42:       PetscErrorCode ierr
     43:       PetscMPIInt  rank
     44:       PetscScalar  one,two,three
     45:       PetscScalar  dots(3),dot
     46:       character*(40)   name

     48: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     49: !                 Beginning of program
     50: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

     52:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
     53:       one   = 1.0
     54:       two   = 2.0
     55:       three = 3.0
     56:       n     = 20
     57:       ithree = 3
     58:       call PetscOptionsGetInt(PETSC_NULL_CHARACTER,'-n',n,flg,ierr)
     59:       call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)

     61: !  Create a vector, specifying only its global dimension.
     62: !  When using VecCreate(), VecSetSizes() and VecSetFromOptions(),
     63: !  the vector format (currently parallel
     64: !  or sequential) is determined at runtime.  Also, the parallel
     65: !  partitioning of the vector is determined by PETSc at runtime.
     66: !
     67: !  Routines for creating particular vector types directly are:
     68: !     VecCreateSeq() - uniprocessor vector
     69: !     VecCreateMPI() - distributed vector, where the user can
     70: !                      determine the parallel partitioning
     71: !     VecCreateShared() - parallel vector that uses shared memory
     72: !                         (available only on the SGI); otherwise,
     73: !                         is the same as VecCreateMPI()
     74: !
     75: !     VecCreate(), VecSetSizes() and VecSetFromOptions() allows one
     76: !                 to determine at runtime which version to use
     77: !                 with the options -vec_type mpi or -vec_type shared
     78: !
     79:       call VecCreate(PETSC_COMM_WORLD,x,ierr)
     80:       call VecSetSizes(x,PETSC_DECIDE,n,ierr)
     81:       call VecSetFromOptions(x,ierr)
     82:       call VecGetType(x,name,ierr)

     84: !  Duplicate some work vectors (of the same format and
     85: !  partitioning as the initial vector).

     87:       call VecDuplicate(x,y,ierr)
     88:       call VecDuplicate(x,w,ierr)

     90: !  Duplicate more work vectors (of the same format and
     91: !  partitioning as the initial vector).  Here we duplicate
     92: !  an array of vectors, which is often more convenient than
     93: !  duplicating individual ones.

     95:       call VecDuplicateVecs(x,ithree,z,ierr)

     97: !  Set the vectors to entries to a constant value.

     99:       call VecSet(x,one,ierr)

    101:       call VecSet(y,two,ierr)
    102:       call VecSet(z(1),one,ierr)
    103:       call VecSet(z(2),two,ierr)
    104:       call VecSet(z(3),three,ierr)

    106: !  Demonstrate various basic vector routines.

    108:       call VecDot(x,x,dot,ierr)
    109:       call VecMDot(x,ithree,z,dots,ierr)

    111: !  Note: If using a complex numbers version of PETSc, then
    112: !  PETSC_USE_COMPLEX is defined in the makefiles; otherwise,
    113: !  (when using real numbers) it is undefined.

    115:       if (rank .eq. 0) then
    116: #if defined(PETSC_USE_COMPLEX)
    117:          write(6,100) int(PetscRealPart(dot))
    118:          write(6,110) int(PetscRealPart(dots(1))),                               &
    119:      &                int(PetscRealPart(dots(2))),                               &
    120:      &                int(PetscRealPart(dots(3)))
    121: #else
    122:          write(6,100) int(dot)
    123:          write(6,110) int(dots(1)),int(dots(2)),int(dots(3))
    124: #endif
    125:          write(6,120)
    126:       endif
    127:  100  format ('Vector length ',i6)
    128:  110  format ('Vector length ',3(i6))
    129:  120  format ('All other values should be near zero')

    131:       call VecScale(x,two,ierr)
    132:       call VecNorm(x,NORM_2,norm,ierr)
    133:       v = norm-2.0*sqrt(dble(n))
    134:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    135:       if (rank .eq. 0) write(6,130) v
    136:  130  format ('VecScale ',1pe8.2)

    138:       call VecCopy(x,w,ierr)
    139:       call VecNorm(w,NORM_2,norm,ierr)
    140:       v = norm-2.0*sqrt(dble(n))
    141:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    142:       if (rank .eq. 0) write(6,140) v
    143:  140  format ('VecCopy ',1pe8.2)

    145:       call VecAXPY(y,three,x,ierr)
    146:       call VecNorm(y,NORM_2,norm,ierr)
    147:       v = norm-8.0*sqrt(dble(n))
    148:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    149:       if (rank .eq. 0) write(6,150) v
    150:  150  format ('VecAXPY ',1pe8.2)

    152:       call VecAYPX(y,two,x,ierr)
    153:       call VecNorm(y,NORM_2,norm,ierr)
    154:       v = norm-18.0*sqrt(dble(n))
    155:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    156:       if (rank .eq. 0) write(6,160) v
    157:  160  format ('VecAYXP ',1pe8.2)

    159:       call VecSwap(x,y,ierr)
    160:       call VecNorm(y,NORM_2,norm,ierr)
    161:       v = norm-2.0*sqrt(dble(n))
    162:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    163:       if (rank .eq. 0) write(6,170) v
    164:  170  format ('VecSwap ',1pe8.2)

    166:       call VecNorm(x,NORM_2,norm,ierr)
    167:       v = norm-18.0*sqrt(dble(n))
    168:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    169:       if (rank .eq. 0) write(6,180) v
    170:  180  format ('VecSwap ',1pe8.2)

    172:       call VecWAXPY(w,two,x,y,ierr)
    173:       call VecNorm(w,NORM_2,norm,ierr)
    174:       v = norm-38.0*sqrt(dble(n))
    175:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    176:       if (rank .eq. 0) write(6,190) v
    177:  190  format ('VecWAXPY ',1pe8.2)

    179:       call VecPointwiseMult(w,y,x,ierr)
    180:       call VecNorm(w,NORM_2,norm,ierr)
    181:       v = norm-36.0*sqrt(dble(n))
    182:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    183:       if (rank .eq. 0) write(6,200) v
    184:  200  format ('VecPointwiseMult ',1pe8.2)

    186:       call VecPointwiseDivide(w,x,y,ierr)
    187:       call VecNorm(w,NORM_2,norm,ierr)
    188:       v = norm-9.0*sqrt(dble(n))
    189:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    190:       if (rank .eq. 0) write(6,210) v
    191:  210  format ('VecPointwiseDivide ',1pe8.2)

    194:       dots(1) = one
    195:       dots(2) = three
    196:       dots(3) = two
    197:       call VecSet(x,one,ierr)
    198:       call VecMAXPY(x,ithree,dots,z,ierr)
    199:       call VecNorm(z(1),NORM_2,norm,ierr)
    200:       v = norm-sqrt(dble(n))
    201:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    202:       call VecNorm(z(2),NORM_2,norm,ierr)
    203:       v1 = norm-2.0*sqrt(dble(n))
    204:       if (v1 .gt. -PETSC_SMALL .and. v1 .lt. PETSC_SMALL) v1 = 0.0
    205:       call VecNorm(z(3),NORM_2,norm,ierr)
    206:       v2 = norm-3.0*sqrt(dble(n))
    207:       if (v2 .gt. -PETSC_SMALL .and. v2 .lt. PETSC_SMALL) v2 = 0.0
    208:       if (rank .eq. 0) write(6,220) v,v1,v2
    209:  220  format ('VecMAXPY ',3(1pe8.2))

    211: !  Free work space.  All PETSc objects should be destroyed when they
    212: !  are no longer needed.

    214:       call VecDestroy(x,ierr)
    215:       call VecDestroy(y,ierr)
    216:       call VecDestroy(w,ierr)
    217:       call VecDestroyVecs(ithree,z,ierr)
    218:       call PetscFinalize(ierr)

    220:       end