Date: 2021-03-03T22:25:59+00:00

Actual source code: ex1f.F90
petsc-3.14.5 2021-03-03
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      1: !
      2: !
      3: !/*T
      4: !   Concepts: vectors^basic routines
      5: !   Processors: n
      6: !T*/
      7: !
      8: ! -----------------------------------------------------------------------

     10:       program main
     11: #include <petsc/finclude/petscvec.h>
     12:       use petscvec
     13:       implicit none

     15: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     16: !                   Variable declarations
     17: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     18: !
     19: !  Variables:
     20: !     x, y, w - vectors
     21: !     z       - array of vectors

     23:       Vec               :: x,y,w
     24:       Vec, dimension(5) :: z
     25:       PetscReal         :: norm,v,v1,v2
     26:       PetscInt, parameter :: &
     27:         ithree = 3, &
     28:         n = 20
     29:       PetscBool         :: flg
     30:       PetscErrorCode    :: ierr
     31:       PetscMPIInt       :: rank
     32:       PetscScalar, parameter :: &
     33:         one = 1.0, &
     34:         two = 2.0, &
     35:         three = 3.0
     36:       PetscScalar :: dot
     37:       PetscScalar, dimension(3) :: dots
     38:       character(len=PETSC_MAX_PATH_LEN) ::  name
     39:       PetscReal    :: nfloat

     41: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
     42: !                 Beginning of program
     43: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

     45:       call PetscInitialize(PETSC_NULL_CHARACTER,ierr)
     46:       if (ierr /= 0) then
     47:         print*,'Unable to initialize PETSc'
     48:         stop
     49:       endif
     50:       call PetscOptionsGetInt(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-n',n,flg,ierr)
     51:       nfloat = n
     52:       call MPI_Comm_rank(PETSC_COMM_WORLD,rank,ierr)

     54: !  Create a vector, specifying only its global dimension.
     55: !  When using VecCreate(), VecSetSizes() and VecSetFromOptions(),
     56: !  the vector format (currently parallel
     57: !  or sequential) is determined at runtime.  Also, the parallel
     58: !  partitioning of the vector is determined by PETSc at runtime.
     59: !
     60: !  Routines for creating particular vector types directly are:
     61: !     VecCreateSeq() - uniprocessor vector
     62: !     VecCreateMPI() - distributed vector, where the user can
     63: !                      determine the parallel partitioning
     64: !     VecCreateShared() - parallel vector that uses shared memory
     65: !                         (available only on the SGI); otherwise,
     66: !                         is the same as VecCreateMPI()
     67: !
     68: !     VecCreate(), VecSetSizes() and VecSetFromOptions() allows one
     69: !                 to determine at runtime which version to use
     70: !                 with the options -vec_type mpi or -vec_type shared
     71: !
     72:       call VecCreate(PETSC_COMM_WORLD,x,ierr)
     73:       call VecSetSizes(x,PETSC_DECIDE,n,ierr)
     74:       call VecSetFromOptions(x,ierr)
     75:       call VecGetType(x,name,ierr)

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

     80:       call VecDuplicate(x,y,ierr)
     81:       call VecDuplicate(x,w,ierr)

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

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

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

     92:       call VecSet(x,one,ierr)

     94:       call VecSet(y,two,ierr)
     95:       call VecSet(z(1),one,ierr)
     96:       call VecSet(z(2),two,ierr)
     97:       call VecSet(z(3),three,ierr)

     99: !  Demonstrate various basic vector routines.

    101:       call VecDot(x,x,dot,ierr)
    102:       call VecMDot(x,ithree,z,dots,ierr)

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

    108:       if (rank .eq. 0) then
    109: #if defined(PETSC_USE_COMPLEX)
    110:          write(6,100) int(PetscRealPart(dot))
    111:          write(6,110) int(PetscRealPart(dots(1))),int(PetscRealPart(dots(2))),int(PetscRealPart(dots(3)))
    112: #else
    113:          write(6,100) int(dot)
    114:          write(6,110) int(dots(1)),int(dots(2)),int(dots(3))
    115: #endif
    116:          write(6,120)
    117:       endif
    118:  100  format ('Vector length ',i6)
    119:  110  format ('Vector length ',3(i6))
    120:  120  format ('All other values should be near zero')

    122:       call VecScale(x,two,ierr)
    123:       call VecNorm(x,NORM_2,norm,ierr)
    124:       v = abs(norm-2.0*sqrt(nfloat))
    125:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    126:       if (rank == 0) write(6,130) v
    127:  130  format ('VecScale ',1pe9.2)

    129:       call VecCopy(x,w,ierr)
    130:       call VecNorm(w,NORM_2,norm,ierr)
    131:       v = abs(norm-2.0*sqrt(nfloat))
    132:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    133:       if (rank == 0) write(6,140) v
    134:  140  format ('VecCopy ',1pe9.2)

    136:       call VecAXPY(y,three,x,ierr)
    137:       call VecNorm(y,NORM_2,norm,ierr)
    138:       v = abs(norm-8.0*sqrt(nfloat))
    139:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    140:       if (rank == 0) write(6,150) v
    141:  150  format ('VecAXPY ',1pe9.2)

    143:       call VecAYPX(y,two,x,ierr)
    144:       call VecNorm(y,NORM_2,norm,ierr)
    145:       v = abs(norm-18.0*sqrt(nfloat))
    146:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    147:       if (rank == 0) write(6,160) v
    148:  160  format ('VecAYXP ',1pe9.2)

    150:       call VecSwap(x,y,ierr)
    151:       call VecNorm(y,NORM_2,norm,ierr)
    152:       v = abs(norm-2.0*sqrt(nfloat))
    153:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    154:       if (rank == 0) write(6,170) v
    155:  170  format ('VecSwap ',1pe9.2)

    157:       call VecNorm(x,NORM_2,norm,ierr)
    158:       v = abs(norm-18.0*sqrt(nfloat))
    159:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    160:       if (rank == 0) write(6,180) v
    161:  180  format ('VecSwap ',1pe9.2)

    163:       call VecWAXPY(w,two,x,y,ierr)
    164:       call VecNorm(w,NORM_2,norm,ierr)
    165:       v = abs(norm-38.0*sqrt(nfloat))
    166:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    167:       if (rank == 0) write(6,190) v
    168:  190  format ('VecWAXPY ',1pe9.2)

    170:       call VecPointwiseMult(w,y,x,ierr)
    171:       call VecNorm(w,NORM_2,norm,ierr)
    172:       v = abs(norm-36.0*sqrt(nfloat))
    173:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    174:       if (rank == 0) write(6,200) v
    175:  200  format ('VecPointwiseMult ',1pe9.2)

    177:       call VecPointwiseDivide(w,x,y,ierr)
    178:       call VecNorm(w,NORM_2,norm,ierr)
    179:       v = abs(norm-9.0*sqrt(nfloat))
    180:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    181:       if (rank == 0) write(6,210) v
    182:  210  format ('VecPointwiseDivide ',1pe9.2)

    185:       dots(1) = one
    186:       dots(2) = three
    187:       dots(3) = two
    188:       call VecSet(x,one,ierr)
    189:       call VecMAXPY(x,ithree,dots,z,ierr)
    190:       call VecNorm(z(1),NORM_2,norm,ierr)
    191:       v = abs(norm-sqrt(nfloat))
    192:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
    193:       call VecNorm(z(2),NORM_2,norm,ierr)
    194:       v1 = abs(norm-2.0*sqrt(nfloat))
    195:       if (v1 .gt. -PETSC_SMALL .and. v1 .lt. PETSC_SMALL) v1 = 0.0
    196:       call VecNorm(z(3),NORM_2,norm,ierr)
    197:       v2 = abs(norm-3.0*sqrt(nfloat))
    198:       if (v2 .gt. -PETSC_SMALL .and. v2 .lt. PETSC_SMALL) v2 = 0.0
    199:       if (rank .eq. 0) write(6,220) v,v1,v2
    200:  220  format ('VecMAXPY ',3(2x,1pe9.2))

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

    205:       call VecDestroy(x,ierr)
    206:       call VecDestroy(y,ierr)
    207:       call VecDestroy(w,ierr)
    208:       call VecDestroyVecs(ithree,z,ierr)
    209:       call PetscFinalize(ierr)

    211:       end

    213: !
    214: !/*TEST
    215: !
    216: !     test:
    217: !       suffix: 1
    218: !
    219: !     test:
    220: !       suffix: 2
    221: !       nsize: 2
    222: !
    223: !TEST*/