Line data    Source code

       1             : /*
       2             :    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       3             :    SLEPc - Scalable Library for Eigenvalue Problem Computations
       4             :    Copyright (c) 2002-, Universitat Politecnica de Valencia, Spain
       5             : 
       6             :    This file is part of SLEPc.
       7             :    SLEPc is distributed under a 2-clause BSD license (see LICENSE).
       8             :    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
       9             : */
      10             : 
      11             : static char help[] = "Tests the case when both arguments of MFNSolve() are the same Vec.\n\n"
      12             :   "The command line options are:\n"
      13             :   "  -t <sval>, where <sval> = scalar value that multiplies the argument.\n"
      14             :   "  -n <n>, where <n> = number of grid subdivisions in x dimension.\n"
      15             :   "  -m <m>, where <m> = number of grid subdivisions in y dimension.\n\n";
      16             : 
      17             : #include <slepcmfn.h>
      18             : 
      19           3 : int main(int argc,char **argv)
      20             : {
      21           3 :   Mat            A;           /* problem matrix */
      22           3 :   MFN            mfn;
      23           3 :   FN             f;
      24           3 :   PetscReal      norm;
      25           3 :   PetscScalar    t=0.3;
      26           3 :   PetscInt       N,n=25,m,Istart,Iend,II,i,j;
      27           3 :   PetscBool      flag;
      28           3 :   Vec            v,y;
      29             : 
      30           3 :   PetscFunctionBeginUser;
      31           3 :   PetscCall(SlepcInitialize(&argc,&argv,NULL,help));
      32             : 
      33           3 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-n",&n,NULL));
      34           3 :   PetscCall(PetscOptionsGetInt(NULL,NULL,"-m",&m,&flag));
      35           3 :   if (!flag) m=n;
      36           3 :   N = n*m;
      37           3 :   PetscCall(PetscOptionsGetScalar(NULL,NULL,"-t",&t,NULL));
      38           3 :   PetscCall(PetscPrintf(PETSC_COMM_WORLD,"\nMatrix exponential y=exp(t*A)*e, of the 2-D Laplacian, N=%" PetscInt_FMT " (%" PetscInt_FMT "x%" PetscInt_FMT " grid)\n\n",N,n,m));
      39             : 
      40             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      41             :                          Build the 2-D Laplacian
      42             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      43             : 
      44           3 :   PetscCall(MatCreate(PETSC_COMM_WORLD,&A));
      45           3 :   PetscCall(MatSetSizes(A,PETSC_DECIDE,PETSC_DECIDE,N,N));
      46           3 :   PetscCall(MatSetFromOptions(A));
      47             : 
      48           3 :   PetscCall(MatGetOwnershipRange(A,&Istart,&Iend));
      49        1878 :   for (II=Istart;II<Iend;II++) {
      50        1875 :     i = II/n; j = II-i*n;
      51        1875 :     if (i>0) PetscCall(MatSetValue(A,II,II-n,-1.0,INSERT_VALUES));
      52        1875 :     if (i<m-1) PetscCall(MatSetValue(A,II,II+n,-1.0,INSERT_VALUES));
      53        1875 :     if (j>0) PetscCall(MatSetValue(A,II,II-1,-1.0,INSERT_VALUES));
      54        1875 :     if (j<n-1) PetscCall(MatSetValue(A,II,II+1,-1.0,INSERT_VALUES));
      55        1875 :     PetscCall(MatSetValue(A,II,II,4.0,INSERT_VALUES));
      56             :   }
      57             : 
      58           3 :   PetscCall(MatAssemblyBegin(A,MAT_FINAL_ASSEMBLY));
      59           3 :   PetscCall(MatAssemblyEnd(A,MAT_FINAL_ASSEMBLY));
      60             : 
      61             :   /* set v = ones(n,1) */
      62           3 :   PetscCall(MatCreateVecs(A,&v,&y));
      63           3 :   PetscCall(VecSet(v,1.0));
      64             : 
      65             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      66             :                 Create the solver and set various options
      67             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      68             : 
      69           3 :   PetscCall(FNCreate(PETSC_COMM_WORLD,&f));
      70           3 :   PetscCall(FNSetType(f,FNEXP));
      71             : 
      72           3 :   PetscCall(MFNCreate(PETSC_COMM_WORLD,&mfn));
      73           3 :   PetscCall(MFNSetOperator(mfn,A));
      74           3 :   PetscCall(MFNSetFN(mfn,f));
      75           3 :   PetscCall(MFNSetErrorIfNotConverged(mfn,PETSC_TRUE));
      76           3 :   PetscCall(MFNSetFromOptions(mfn));
      77             : 
      78             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      79             :                       Solve the problem, y=exp(t*A)*v
      80             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      81             : 
      82           3 :   PetscCall(FNSetScale(f,t,1.0));
      83           3 :   PetscCall(MFNSolve(mfn,v,y));
      84           3 :   PetscCall(VecNorm(y,NORM_2,&norm));
      85           3 :   PetscCall(PetscPrintf(PETSC_COMM_WORLD," Computed vector at time t=%.4g has norm %g\n\n",(double)PetscRealPart(t),(double)norm));
      86             : 
      87             :   /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      88             :            Repeat the computation in two steps, overwriting v:
      89             :               v=exp(0.5*t*A)*v,  v=exp(0.5*t*A)*v
      90             :      - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
      91             : 
      92           3 :   PetscCall(FNSetScale(f,0.5*t,1.0));
      93           3 :   PetscCall(MFNSolve(mfn,v,v));
      94           3 :   PetscCall(MFNSolve(mfn,v,v));
      95             :   /* compute norm of difference */
      96           3 :   PetscCall(VecAXPY(y,-1.0,v));
      97           3 :   PetscCall(VecNorm(y,NORM_2,&norm));
      98           3 :   if (norm<100*PETSC_MACHINE_EPSILON) PetscCall(PetscPrintf(PETSC_COMM_WORLD," The norm of the difference is <100*eps\n\n"));
      99           0 :   else PetscCall(PetscPrintf(PETSC_COMM_WORLD," The norm of the difference is %g\n\n",(double)norm));
     100             : 
     101             :   /*
     102             :      Free work space
     103             :   */
     104           3 :   PetscCall(MFNDestroy(&mfn));
     105           3 :   PetscCall(FNDestroy(&f));
     106           3 :   PetscCall(MatDestroy(&A));
     107           3 :   PetscCall(VecDestroy(&v));
     108           3 :   PetscCall(VecDestroy(&y));
     109           3 :   PetscCall(SlepcFinalize());
     110             :   return 0;
     111             : }
     112             : 
     113             : /*TEST
     114             : 
     115             :    testset:
     116             :       args: -mfn_type {{krylov expokit}}
     117             :       output_file: output/test2_1.out
     118             :       test:
     119             :          suffix: 1
     120             :       test:
     121             :          suffix: 1_cuda
     122             :          args: -mat_type aijcusparse
     123             :          requires: cuda
     124             :       test:
     125             :          suffix: 1_hip
     126             :          args: -mat_type aijhipsparse
     127             :          requires: hip
     128             : 
     129             :    test:
     130             :       suffix: 3
     131             :       args: -mfn_type expokit -t 0.6 -mfn_ncv 24
     132             :       requires: !__float128
     133             : 
     134             : TEST*/