Actual source code: ex1f.F

  1: !
  2: !   Program usage:  mpirun ex1f [-help] [all PETSc options]
  3: !
  4: !/*T
  5: !   Concepts: vectors^basic routines
  6: !   Processors: n
  7: !T*/
  8: !
  9: ! -----------------------------------------------------------------------

 11:       program main
 12:       implicit none

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

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

 39:       Vec              x,y,w,z(5)
 40:       PetscReal        norm,v,v1,v2
 41:       PetscInt           n,ithree
 42:       PetscTruth flg
 43:       PetscErrorCode ierr
 44:       PetscMPIInt  rank
 45:       PetscScalar      one,two,three,dots(3),dot
 46:       character*(80)   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)
 83:       print*,name
 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(one,x,ierr)
100:       call VecSet(two,y,ierr)
101:       call VecSet(one,z(1),ierr)
102:       call VecSet(two,z(2),ierr)
103:       call VecSet(three,z(3),ierr)

105: !  Demonstrate various basic vector routines.

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

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

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

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

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

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

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

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

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

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

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

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

192: 
193:       dots(1) = one
194:       dots(2) = three
195:       dots(3) = two
196:       call VecSet(one,x,ierr)
197:       call VecMAXPY(ithree,dots,x,z,ierr)
198:       call VecNorm(z(1),NORM_2,norm,ierr)
199:       v = norm-sqrt(dble(n))
200:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
201:       call VecNorm(z(2),NORM_2,norm,ierr)
202:       v1 = norm-2.0*sqrt(dble(n))
203:       if (v1 .gt. -PETSC_SMALL .and. v1 .lt. PETSC_SMALL) v1 = 0.0
204:       call VecNorm(z(3),NORM_2,norm,ierr)
205:       v2 = norm-3.0*sqrt(dble(n))
206:       if (v2 .gt. -PETSC_SMALL .and. v2 .lt. PETSC_SMALL) v2 = 0.0
207:       if (rank .eq. 0) write(6,220) v,v1,v2
208:  220  format ('VecMAXPY ',3(1pe8.2))


211: !  Test whether vector has been corrupted (just to demonstrate this
212: !  routine) not needed in most application codes.

214:       call VecValid(x,flg,ierr)
215:       if (flg .ne. PETSC_TRUE) then
216:          if (rank .eq. 0) then
217:             write(6,*) 'Corrupted vector!'
218:          endif
219:          SETERRQ(1,' ',ierr)
220:       endif

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

225:       call VecDestroy(x,ierr)
226:       call VecDestroy(y,ierr)
227:       call VecDestroy(w,ierr)
228:       call VecDestroyVecs(z,ithree,ierr)
229:       call PetscFinalize(ierr)

231:       end
232: