C++ (Cpp) PetscCeilReal Examples

Example #1

File: ex19.c Project: OpenCMISS-Dependencies/slepc

PetscErrorCode GetExactEigenvalues(PetscInt M,PetscInt N,PetscInt P,PetscInt nconv,PetscReal *exact)
{
  PetscInt       n,i,j,k,l;
  PetscReal      *evals,ax,ay,az,sx,sy,sz;
  PetscErrorCode ierr;

  PetscFunctionBeginUser;
  ax = PETSC_PI/2/(M+1);
  ay = PETSC_PI/2/(N+1);
  az = PETSC_PI/2/(P+1);
  n = PetscCeilReal(PetscPowReal(nconv,0.33333)+1);
  ierr = PetscMalloc1(n*n*n,&evals);CHKERRQ(ierr);
  l = 0;
  for (i=1;i<=n;i++) {
    sx = PetscSinReal(ax*i);
    for (j=1;j<=n;j++) {
      sy = PetscSinReal(ay*j);
      for (k=1;k<=n;k++) {
        sz = PetscSinReal(az*k);
        evals[l++] = 4.0*(sx*sx+sy*sy+sz*sz);
      }
    }
  }
  ierr = PetscSortReal(n*n*n,evals);CHKERRQ(ierr);
  for (i=0;i<nconv;i++) exact[i] = evals[i];
  ierr = PetscFree(evals);CHKERRQ(ierr);
  PetscFunctionReturn(0);
}

Example #2

File: sampler.c Project: hpgmg/hpgmg

// Find the squarest grid, with best[0] <= best[1] <= best[2].
PetscErrorCode ProcessGridFindSquarest(PetscMPIInt nranks,PetscInt best[3]) {
  PetscMPIInt target,s,a,b,c;

  PetscFunctionBegin;
  target = PetscCeilReal(PetscPowReal(nranks,1./3));
  if (target*target*target > nranks) target--; // if ceil was overzealous
  for (a=target; a>=1; a--) {
    if (nranks%a) continue; // Not a candidate factor
    s = PetscCeilReal(PetscSqrtReal(nranks/a));
    if (s*s > nranks/a) s--; // If our ceil was overzealous
    for (b=s; b>=a; b--) {
      if (nranks/a % b == 0) {  // The first proper divisor is the one I want
        c = nranks/a/b;
        best[0] = a;
        best[1] = b;
        best[2] = c;
        PetscFunctionReturn(0);
      }
    }
  }
  SETERRQ(PETSC_COMM_WORLD,PETSC_ERR_ARG_INCOMP,"Could not find squarest grid");
  PetscFunctionReturn(0);
}