Actual source code: ex54f.F90
1: ! Solve the system for (x,y,z):
2: ! x + y + z = 6
3: ! x - y + z = 2
4: ! x + y - z = 0
5: ! x + y + 2*z = 9 This equation is used if DMS=4 (else set DMS=3)
6: ! => x=1 , y=2 , z=3
8: program main
9: #include "petsc/finclude/petsc.h"
10: use petsc
11: implicit none
13: PetscInt:: IR(1), IC(1), I, J, DMS = 4 ! Set DMS=3 for a 3x3 squared system
14: PetscErrorCode ierr
15: PetscReal :: MV(12), X(3), B(4), BI(1)
16: Mat:: MTX
17: Vec:: PTCB, PTCX
18: KSP:: KK
19: PetscInt one, three
21: PetscCallA(PetscInitialize(ierr))
22: one = 1
23: three = 3
24: PetscCallA(MatCreate(PETSC_COMM_WORLD, mtx, ierr))
25: PetscCallA(MatSetSizes(mtx, PETSC_DECIDE, PETSC_DECIDE, DMS, three, ierr))
26: PetscCallA(MatSetFromOptions(mtx, ierr))
27: PetscCallA(MatSetUp(mtx, ierr))
28: PetscCallA(MatSetOption(mtx, MAT_NEW_NONZERO_ALLOCATION_ERR, PETSC_FALSE, ierr))
29: MV = (/1., 1., 1., 1., -1., 1., 1., 1., -1., 1., 1., 2./)
31: do J = 1, 3
32: do I = 1, DMS
33: IR(1) = I - 1; IC(1) = J - 1; X(1) = MV(J + (I - 1)*3)
34: PetscCallA(MatSetValues(MTX, one, IR, one, IC, X, INSERT_VALUES, ierr))
35: end do
36: end do
38: PetscCallA(MatAssemblyBegin(MTX, MAT_FINAL_ASSEMBLY, ierr))
39: PetscCallA(MatAssemblyEnd(MTX, MAT_FINAL_ASSEMBLY, ierr))
41: X = 0.; B = (/6., 2., 0., 9./)
42: PetscCallA(VecCreate(PETSC_COMM_WORLD, PTCB, ierr)) ! RHS vector
43: PetscCallA(VecSetSizes(PTCB, PETSC_DECIDE, DMS, ierr))
44: PetscCallA(VecSetFromOptions(PTCB, ierr))
46: do I = 1, DMS
47: IR(1) = I - 1
48: BI(1) = B(i)
49: PetscCallA(VecSetValues(PTCB, one, IR, BI, INSERT_VALUES, ierr))
50: end do
52: PetscCallA(vecAssemblyBegin(PTCB, ierr))
53: PetscCallA(vecAssemblyEnd(PTCB, ierr))
55: PetscCallA(VecCreate(PETSC_COMM_WORLD, PTCX, ierr)) ! Solution vector
56: PetscCallA(VecSetSizes(PTCX, PETSC_DECIDE, three, ierr))
57: PetscCallA(VecSetFromOptions(PTCX, ierr))
58: PetscCallA(vecAssemblyBegin(PTCX, ierr))
59: PetscCallA(vecAssemblyEnd(PTCX, ierr))
61: PetscCallA(KSPCreate(PETSC_COMM_WORLD, KK, ierr))
62: PetscCallA(KSPSetOperators(KK, MTX, MTX, ierr))
63: PetscCallA(KSPSetFromOptions(KK, ierr))
64: PetscCallA(KSPSetUp(KK, ierr))
65: PetscCallA(KSPSolve(KK, PTCB, PTCX, ierr))
66: PetscCallA(VecView(PTCX, PETSC_VIEWER_STDOUT_WORLD, ierr))
68: PetscCallA(MatDestroy(MTX, ierr))
69: PetscCallA(KSPDestroy(KK, ierr))
70: PetscCallA(VecDestroy(PTCB, ierr))
71: PetscCallA(VecDestroy(PTCX, ierr))
72: PetscCallA(PetscFinalize(ierr))
73: end program main
75: !/*TEST
76: ! build:
77: ! requires: !complex
78: ! test:
79: ! args: -ksp_type cgls -pc_type none
80: !
81: !TEST*/