PetscErrorCode KSPComputeEigenvalues_CG(KSP ksp,PetscInt nmax,PetscReal *r,PetscReal *c,PetscInt *neig)
{
KSP_CG *cgP = (KSP_CG*)ksp->data;
PetscScalar *d,*e;
PetscReal *ee;
PetscErrorCode ierr;
PetscInt j,n = ksp->its;
PetscFunctionBegin;
if (nmax < n) SETERRQ(PetscObjectComm((PetscObject)ksp),PETSC_ERR_ARG_SIZ,"Not enough room in work space r and c for eigenvalues");
*neig = n;
ierr = PetscMemzero(c,nmax*sizeof(PetscReal));CHKERRQ(ierr);
if (!n) {
PetscFunctionReturn(0);
}
d = cgP->d; e = cgP->e; ee = cgP->ee;
/* copy tridiagonal matrix to work space */
for (j=0; j<n; j++) {
r[j] = PetscRealPart(d[j]);
ee[j] = PetscRealPart(e[j]);
}
LINPACKcgtql1(&n,r,ee,&j);
if (j != 0) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error from tql1(); eispack eigenvalue routine");
ierr = PetscSortReal(n,r);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
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);
}
/*@
PetscSortRemoveDupsReal - Sorts an array of doubles in place in increasing order removes all duplicate entries
Not Collective
Input Parameters:
+ n - number of values
- v - array of doubles
Output Parameter:
. n - number of non-redundant values
Level: intermediate
Concepts: sorting^doubles
.seealso: PetscSortReal(), PetscSortRemoveDupsInt()
@*/
PetscErrorCode PetscSortRemoveDupsReal(PetscInt *n,PetscReal v[])
{
PetscErrorCode ierr;
PetscInt i,s = 0,N = *n, b = 0;
PetscFunctionBegin;
ierr = PetscSortReal(N,v);CHKERRQ(ierr);
for (i=0; i<N-1; i++) {
if (v[b+s+1] != v[b]) {
v[b+1] = v[b+s+1]; b++;
} else s++;
}
*n = N - s;
PetscFunctionReturn(0);
}
void PETSC_STDCALL petscsortreal_(PetscInt *n,PetscReal v[], int *__ierr ){
*__ierr = PetscSortReal(*n,v);
}
