Actual source code: ex1f.F90

petsc-master 2019-08-22
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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=40) ::  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*/