xref: /petsc/src/mat/tutorials/ex1.c (revision c4762a1b19cd2af06abeed90e8f9d34fb975dd94)
1*c4762a1bSJed Brown 
2*c4762a1bSJed Brown static char help[] = "Reads a PETSc matrix and vector from a file and reorders it.\n\
3*c4762a1bSJed Brown   -f0 <input_file> : first file to load (small system)\n\
4*c4762a1bSJed Brown   -f1 <input_file> : second file to load (larger system)\n\n";
5*c4762a1bSJed Brown 
6*c4762a1bSJed Brown /*T
7*c4762a1bSJed Brown    Concepts: Mat^ordering a matrix - loading a binary matrix and vector;
8*c4762a1bSJed Brown    Concepts: Mat^loading a binary matrix and vector;
9*c4762a1bSJed Brown    Concepts: Vectors^loading a binary vector;
10*c4762a1bSJed Brown    Concepts: PetscLog^preloading executable
11*c4762a1bSJed Brown    Processors: 1
12*c4762a1bSJed Brown T*/
13*c4762a1bSJed Brown 
14*c4762a1bSJed Brown /*
15*c4762a1bSJed Brown   Include "petscmat.h" so that we can use matrices.
16*c4762a1bSJed Brown   automatically includes:
17*c4762a1bSJed Brown      petscsys.h       - base PETSc routines   petscvec.h    - vectors
18*c4762a1bSJed Brown      petscmat.h    - matrices
19*c4762a1bSJed Brown      petscis.h     - index sets            petscviewer.h - viewers
20*c4762a1bSJed Brown */
21*c4762a1bSJed Brown #include <petscmat.h>
22*c4762a1bSJed Brown 
23*c4762a1bSJed Brown int main(int argc,char **args)
24*c4762a1bSJed Brown {
25*c4762a1bSJed Brown   Mat             A;                      /* matrix */
26*c4762a1bSJed Brown   PetscViewer     fd;                     /* viewer */
27*c4762a1bSJed Brown   char            file[PETSC_MAX_PATH_LEN];           /* input file name */
28*c4762a1bSJed Brown   IS              isrow,iscol;            /* row and column permutations */
29*c4762a1bSJed Brown   PetscErrorCode  ierr;
30*c4762a1bSJed Brown   MatOrderingType rtype = MATORDERINGRCM;
31*c4762a1bSJed Brown   PetscBool       flg;
32*c4762a1bSJed Brown 
33*c4762a1bSJed Brown   ierr = PetscInitialize(&argc,&args,(char*)0,help);if (ierr) return ierr;
34*c4762a1bSJed Brown   /*
35*c4762a1bSJed Brown      Determine files from which we read the two linear systems
36*c4762a1bSJed Brown      (matrix and right-hand-side vector).
37*c4762a1bSJed Brown   */
38*c4762a1bSJed Brown   ierr = PetscOptionsGetString(NULL,NULL,"-f",file,PETSC_MAX_PATH_LEN,&flg);CHKERRQ(ierr);
39*c4762a1bSJed Brown   if (!flg) SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_USER,"Must indicate binary file with the -f option");
40*c4762a1bSJed Brown 
41*c4762a1bSJed Brown   /* -----------------------------------------------------------
42*c4762a1bSJed Brown                   Beginning of loop
43*c4762a1bSJed Brown      ----------------------------------------------------------- */
44*c4762a1bSJed Brown   /*
45*c4762a1bSJed Brown      Loop through the reordering 2 times.
46*c4762a1bSJed Brown       - The intention here is to preload and solve a small system;
47*c4762a1bSJed Brown         then load another (larger) system and solve it as well.
48*c4762a1bSJed Brown         This process preloads the instructions with the smaller
49*c4762a1bSJed Brown         system so that more accurate performance monitoring (via
50*c4762a1bSJed Brown         -log_view) can be done with the larger one (that actually
51*c4762a1bSJed Brown         is the system of interest).
52*c4762a1bSJed Brown   */
53*c4762a1bSJed Brown 
54*c4762a1bSJed Brown   /* - - - - - - - - - - - New Stage - - - - - - - - - - - - -
55*c4762a1bSJed Brown                          Load system i
56*c4762a1bSJed Brown    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
57*c4762a1bSJed Brown 
58*c4762a1bSJed Brown   /*
59*c4762a1bSJed Brown      Open binary file.  Note that we use FILE_MODE_READ to indicate
60*c4762a1bSJed Brown      reading from this file.
61*c4762a1bSJed Brown   */
62*c4762a1bSJed Brown   ierr = PetscViewerBinaryOpen(PETSC_COMM_WORLD,file,FILE_MODE_READ,&fd);CHKERRQ(ierr);
63*c4762a1bSJed Brown 
64*c4762a1bSJed Brown   /*
65*c4762a1bSJed Brown      Load the matrix; then destroy the viewer.
66*c4762a1bSJed Brown   */
67*c4762a1bSJed Brown   ierr = MatCreate(PETSC_COMM_WORLD,&A);CHKERRQ(ierr);
68*c4762a1bSJed Brown   ierr = MatSetType(A,MATSEQAIJ);CHKERRQ(ierr);
69*c4762a1bSJed Brown   ierr = MatLoad(A,fd);CHKERRQ(ierr);
70*c4762a1bSJed Brown   ierr = PetscViewerDestroy(&fd);CHKERRQ(ierr);
71*c4762a1bSJed Brown 
72*c4762a1bSJed Brown   ierr = MatGetOrdering(A,rtype,&isrow,&iscol);CHKERRQ(ierr);
73*c4762a1bSJed Brown   ierr = ISView(isrow,PETSC_VIEWER_STDOUT_WORLD);CHKERRQ(ierr);
74*c4762a1bSJed Brown 
75*c4762a1bSJed Brown   /*
76*c4762a1bSJed Brown      Free work space.  All PETSc objects should be destroyed when they
77*c4762a1bSJed Brown      are no longer needed.
78*c4762a1bSJed Brown   */
79*c4762a1bSJed Brown   ierr = MatDestroy(&A);CHKERRQ(ierr);
80*c4762a1bSJed Brown   ierr = ISDestroy(&isrow);CHKERRQ(ierr);
81*c4762a1bSJed Brown   ierr = ISDestroy(&iscol);CHKERRQ(ierr);
82*c4762a1bSJed Brown 
83*c4762a1bSJed Brown   ierr = PetscFinalize();
84*c4762a1bSJed Brown   return ierr;
85*c4762a1bSJed Brown }
86*c4762a1bSJed Brown 
87*c4762a1bSJed Brown 
88*c4762a1bSJed Brown 
89*c4762a1bSJed Brown /*TEST
90*c4762a1bSJed Brown 
91*c4762a1bSJed Brown    test:
92*c4762a1bSJed Brown       requires: datafilespath double !complex !define(PETSC_USE_64BIT_INDICES)
93*c4762a1bSJed Brown       args: -f ${DATAFILESPATH}/matrices/medium -viewer_binary_skip_info
94*c4762a1bSJed Brown 
95*c4762a1bSJed Brown TEST*/
96