Actual source code: ex1f.F

  1: !
  2: !    "$Id: ex1f.F,v 1.33 2001/08/10 18:41:04 balay Exp $"
  3: !
  4: !   Program usage:  mpirun ex1f [-help] [all PETSc options]
  5: !
  6: !/*T
  7: !   Concepts: vectors^basic routines
  8: !   Processors: n
  9: !T*/
 10: !
 11: ! -----------------------------------------------------------------------

 13:       program main
 14:       implicit none

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

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

 41:       Vec              x,y,w,z(5)
 42:       PetscReal        norm,v,v1,v2
 43:       integer          n,ierr,flg,rank
 44:       PetscScalar      one,two,three,dots(3),dot

 46: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 47: !                 Beginning of program
 48: ! - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

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

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

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

 83:       call VecDuplicate(x,y,ierr)
 84:       call VecDuplicate(x,w,ierr)

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

 91:       call VecDuplicateVecs(x,3,z,ierr)

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

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

101: !  Demonstrate various basic vector routines.

103:       call VecDot(x,x,dot,ierr)
104:       call VecMDot(3,x,z,dots,ierr)

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

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

126:       call VecScale(two,x,ierr)
127:       call VecNorm(x,NORM_2,norm,ierr)
128:       v = norm-2.0*sqrt(dble(n))
129:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
130:       if (rank .eq. 0) write(6,130) v
131:  130  format ("VecScale ",1pe8.2)

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

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

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

154:       call VecSwap(x,y,ierr)
155:       call VecNorm(y,NORM_2,norm,ierr)
156:       v = norm-2.0*sqrt(dble(n))
157:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
158:       if (rank .eq. 0) write(6,170) v
159:  170  format ("VecSwap ",1pe8.2)

161:       call VecNorm(x,NORM_2,norm,ierr)
162:       v = norm-18.0*sqrt(dble(n))
163:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
164:       if (rank .eq. 0) write(6,180) v
165:  180  format ("VecSwap ",1pe8.2)

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

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

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

188: 
189:       dots(1) = one
190:       dots(2) = three
191:       dots(3) = two
192:       call VecSet(one,x,ierr)
193:       call VecMAXPY(3,dots,x,z,ierr)
194:       call VecNorm(z(1),NORM_2,norm,ierr)
195:       v = norm-sqrt(dble(n))
196:       if (v .gt. -PETSC_SMALL .and. v .lt. PETSC_SMALL) v = 0.0
197:       call VecNorm(z(2),NORM_2,norm,ierr)
198:       v1 = norm-2.0*sqrt(dble(n))
199:       if (v1 .gt. -PETSC_SMALL .and. v1 .lt. PETSC_SMALL) v1 = 0.0
200:       call VecNorm(z(3),NORM_2,norm,ierr)
201:       v2 = norm-3.0*sqrt(dble(n))
202:       if (v2 .gt. -PETSC_SMALL .and. v2 .lt. PETSC_SMALL) v2 = 0.0
203:       if (rank .eq. 0) write(6,220) v,v1,v2
204:  220  format ("VecMAXPY ",3(1pe8.2))


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

210:       call VecValid(x,flg,ierr)
211:       if (flg .ne. PETSC_TRUE) then
212:          if (rank .eq. 0) then
213:             write(6,*) 'Corrupted vector!'
214:          endif
215:          SETERRQ(1,' ',ierr)
216:       endif

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

221:       call VecDestroy(x,ierr)
222:       call VecDestroy(y,ierr)
223:       call VecDestroy(w,ierr)
224:       call VecDestroyVecs(z,3,ierr)
225:       call PetscFinalize(ierr)

227:       end
228: