1! 2 program main 3#include <petsc/finclude/petscksp.h> 4 use petscksp 5 implicit none 6 7! 8! This example is a modified Fortran version of ex6.c. It tests the use of 9! options prefixes in PETSc. Two linear problems are solved in this program. 10! The first problem is read from a file. The second problem is constructed 11! from the first, by eliminating some of the entries of the linear matrix 'A'. 12 13! Each solve is distinguished by a unique prefix - 'a' for the first, 'b' 14! for the second. With the prefix the user can distinguish between the various 15! options (command line, from .petscrc file, etc.) for each of the solvers. 16! Input arguments are: 17! -f <input_file> : file to load. For a 5X5 example of the 5-pt. stencil 18! use the file petsc/src/mat/examples/mat.ex.binary 19 20 PetscErrorCode ierr 21 PetscInt its,ione,ifive,izero 22 PetscBool flg 23 PetscScalar none,five 24 PetscReal norm 25 Vec x,b,u 26 Mat A 27 KSP ksp1,ksp2 28 character*(PETSC_MAX_PATH_LEN) f 29 PetscViewer fd 30 IS isrow 31 none = -1.0 32 five = 5.0 33 ifive = 5 34 ione = 1 35 izero = 0 36 37 PetscCallA(PetscInitialize(ierr)) 38 39! Read in matrix and RHS 40 PetscCallA(PetscOptionsGetString(PETSC_NULL_OPTIONS,PETSC_NULL_CHARACTER,'-f',f,flg,ierr)) 41 PetscCallA(PetscViewerBinaryOpen(PETSC_COMM_WORLD,f,FILE_MODE_READ,fd,ierr)) 42 43 PetscCallA(MatCreate(PETSC_COMM_WORLD,A,ierr)) 44 PetscCallA(MatSetType(A, MATSEQAIJ,ierr)) 45 PetscCallA(MatLoad(A,fd,ierr)) 46 47 PetscCallA(VecCreate(PETSC_COMM_WORLD,b,ierr)) 48 PetscCallA(VecLoad(b,fd,ierr)) 49 PetscCallA(PetscViewerDestroy(fd,ierr)) 50 51! Set up solution 52 PetscCallA(VecDuplicate(b,x,ierr)) 53 PetscCallA(VecDuplicate(b,u,ierr)) 54 55! Solve system-1 56 PetscCallA(KSPCreate(PETSC_COMM_WORLD,ksp1,ierr)) 57 PetscCallA(KSPSetOptionsPrefix(ksp1,'a',ierr)) 58 PetscCallA(KSPAppendOptionsPrefix(ksp1,'_',ierr)) 59 PetscCallA(KSPSetOperators(ksp1,A,A,ierr)) 60 PetscCallA(KSPSetFromOptions(ksp1,ierr)) 61 PetscCallA(KSPSolve(ksp1,b,x,ierr)) 62 63! Show result 64 PetscCallA(MatMult(A,x,u,ierr)) 65 PetscCallA(VecAXPY(u,none,b,ierr)) 66 PetscCallA(VecNorm(u,NORM_2,norm,ierr)) 67 PetscCallA(KSPGetIterationNumber(ksp1,its,ierr)) 68 69 write(6,100) norm,its 70 100 format('Residual norm ',e11.4,' iterations ',i5) 71 72! Create system 2 by striping off some rows of the matrix 73 PetscCallA(ISCreateStride(PETSC_COMM_SELF,ifive,izero,ione,isrow,ierr)) 74 PetscCallA(MatZeroRowsIS(A,isrow,five,PETSC_NULL_VEC,PETSC_NULL_VEC,ierr)) 75 76! Solve system-2 77 PetscCallA(KSPCreate(PETSC_COMM_WORLD,ksp2,ierr)) 78 PetscCallA(KSPSetOptionsPrefix(ksp2,'b',ierr)) 79 PetscCallA(KSPAppendOptionsPrefix(ksp2,'_',ierr)) 80 PetscCallA(KSPSetOperators(ksp2,A,A,ierr)) 81 PetscCallA(KSPSetFromOptions(ksp2,ierr)) 82 PetscCallA(KSPSolve(ksp2,b,x,ierr)) 83 84! Show result 85 PetscCallA(MatMult(A,x,u,ierr)) 86 PetscCallA(VecAXPY(u,none,b,ierr)) 87 PetscCallA(VecNorm(u,NORM_2,norm,ierr)) 88 PetscCallA(KSPGetIterationNumber(ksp2,its,ierr)) 89 write(6,100) norm,its 90 91! Cleanup 92 PetscCallA(KSPDestroy(ksp1,ierr)) 93 PetscCallA(KSPDestroy(ksp2,ierr)) 94 PetscCallA(VecDestroy(b,ierr)) 95 PetscCallA(VecDestroy(x,ierr)) 96 PetscCallA(VecDestroy(u,ierr)) 97 PetscCallA(MatDestroy(A,ierr)) 98 PetscCallA(ISDestroy(isrow,ierr)) 99 100 PetscCallA(PetscFinalize(ierr)) 101 end 102 103!/*TEST 104! 105! test: 106! args: -f ${DATAFILESPATH}/matrices/arco1 -options_left no 107! requires: datafilespath double !complex !defined(PETSC_USE_64BIT_INDICES) 108! 109!TEST*/ 110