/*
SLEPc eigensolver: "krylovschur"
Method: Krylov-Schur with spectrum slicing for symmetric eigenproblems
References:
[1] R.G. Grimes et al., "A shifted block Lanczos algorithm for solving
sparse symmetric generalized eigenproblems", SIAM J. Matrix Analysis
and App., 15(1), pp. 228–272, 1994.
[2] C. Campos and J. E. Roman, "Spectrum slicing strategies based on
restarted Lanczos methods", Numer. Algor., 2012.
DOI: 10.1007/s11075-012-9564-z
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
SLEPc - Scalable Library for Eigenvalue Problem Computations
Copyright (c) 2002-2011, Universitat Politecnica de Valencia, Spain
This file is part of SLEPc.
SLEPc is free software: you can redistribute it and/or modify it under the
terms of version 3 of the GNU Lesser General Public License as published by
the Free Software Foundation.
SLEPc is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with SLEPc. If not, see <http://www.gnu.org/licenses/>.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
#include <slepc-private/epsimpl.h> /*I "slepceps.h" I*/
#include <slepcblaslapack.h>
#include <slepc-private/psimpl.h>
/* Type of data characterizing a shift (place from where an eps is applied) */
typedef struct _n_shift *shift;
struct _n_shift{
PetscReal value;
PetscInt inertia;
PetscBool comp[2]; /* Shows completion of subintervals (left and right) */
shift neighb[2];/* Adjacent shifts */
PetscInt index;/* Index in eig where found values are stored */
PetscInt neigs; /* Number of values found */
PetscReal ext[2]; /* Limits for accepted values */
PetscInt nsch[2]; /* Number of missing values for each subinterval */
PetscInt nconv[2]; /* Converged on each side (accepted or not)*/
PetscBool expf;
};
/* Type of data for storing the state of spectrum slicing*/
struct _n_SR{
PetscReal int0,int1; /* Extremes of the interval */
PetscInt dir; /* Determines the order of values in eig (+1 incr, -1 decr) */
PetscBool hasEnd; /* Tells whether the interval has an end */
PetscInt inertia0,inertia1;
Vec *V;
PetscScalar *eig,*eigi,*monit,*back;
PetscReal *errest;
PetscInt *perm;/* Permutation for keeping the eigenvalues in order */
PetscInt numEigs; /* Number of eigenvalues in the interval */
PetscInt indexEig;
shift sPres; /* Present shift */
shift *pending;/* Pending shifts array */
PetscInt nPend;/* Number of pending shifts */
PetscInt maxPend;/* Size of "pending" array */
Vec *VDef; /* Vector for deflation */
PetscInt *idxDef;/* For deflation */
PetscInt nMAXCompl;
PetscInt iterCompl;
PetscInt itsKs; /* Krylovschur restarts */
PetscInt nleap;
shift s0;/* Initial shift */
PetscScalar *S;/* Matrix for projected problem */
PetscInt nS;
PetscReal beta;
shift sPrev;
};
typedef struct _n_SR *SR;
/*
Fills the fields of a shift structure
*/
#undef __FUNCT__
#define __FUNCT__ "EPSCreateShift"
static PetscErrorCode EPSCreateShift(EPS eps,PetscReal val, shift neighb0,shift neighb1)
{
PetscErrorCode ierr;
shift s,*pending2;
PetscInt i;
SR sr;
PetscFunctionBegin;
sr = (SR)(eps->data);
ierr = PetscMalloc(sizeof(struct _n_shift),&s);CHKERRQ(ierr);
s->value = val;
s->neighb[0] = neighb0;
if(neighb0) neighb0->neighb[1] = s;
s->neighb[1] = neighb1;
if(neighb1) neighb1->neighb[0] = s;
s->comp[0] = PETSC_FALSE;
s->comp[1] = PETSC_FALSE;
s->index = -1;
s->neigs = 0;
s->nconv[0] = s->nconv[1] = 0;
s->nsch[0] = s->nsch[1]=0;
/* Inserts in the stack of pending shifts */
/* If needed, the array is resized */
if(sr->nPend >= sr->maxPend){
sr->maxPend *= 2;
ierr = PetscMalloc((sr->maxPend)*sizeof(shift),&pending2);CHKERRQ(ierr);
for(i=0;i < sr->nPend; i++)pending2[i] = sr->pending[i];
ierr = PetscFree(sr->pending);CHKERRQ(ierr);
sr->pending = pending2;
}
sr->pending[sr->nPend++]=s;
PetscFunctionReturn(0);
}
/* Provides next shift to be computed */
#undef __FUNCT__
#define __FUNCT__ "EPSExtractShift"
static PetscErrorCode EPSExtractShift(EPS eps){
PetscErrorCode ierr;
PetscInt iner,dir,i,k,ld;
PetscScalar *A;
Mat F;
PC pc;
KSP ksp;
SR sr;
PetscFunctionBegin;
sr = (SR)(eps->data);
if(sr->nPend > 0){
sr->sPrev = sr->sPres;
sr->sPres = sr->pending[--sr->nPend];
ierr = STSetShift(eps->OP, sr->sPres->value);CHKERRQ(ierr);
ierr = STGetKSP(eps->OP, &ksp);CHKERRQ(ierr);
ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
ierr = PCFactorGetMatrix(pc,&F);CHKERRQ(ierr);
ierr = MatGetInertia(F,&iner,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
sr->sPres->inertia = iner;
eps->target = sr->sPres->value;
eps->reason = EPS_CONVERGED_ITERATING;
eps->its = 0;
sr->sPres->expf = PETSC_FALSE;
/* For rational Krylov */
if(sr->nS >0 && (sr->sPrev == sr->sPres->neighb[0] || sr->sPrev == sr->sPres->neighb[1]) ){
ierr = PSGetLeadingDimension(eps->ps,&ld);CHKERRQ(ierr);
dir = (sr->sPres->neighb[0] == sr->sPrev)?1:-1;
dir*=sr->dir;
k = 0;
for(i=0;i<sr->nS;i++){
if(dir*PetscRealPart(sr->S[i])>0.0){
sr->S[k] = sr->S[i];
sr->S[sr->nS+k] = sr->S[sr->nS+i];
ierr = VecCopy(eps->V[eps->nconv+i],eps->V[k++]);CHKERRQ(ierr);
if(k>=sr->nS/2)break;
}
}
/* Copy to PS */
ierr = PSGetArray(eps->ps,PS_MAT_A,&A);CHKERRQ(ierr);
ierr = PetscMemzero(A,ld*ld*sizeof(PetscScalar));
for(i=0;i<k;i++){
A[i*(1+ld)] = sr->S[i];
A[k+i*ld] = sr->S[sr->nS+i];
}
sr->nS = k;
ierr = PSRestoreArray(eps->ps,PS_MAT_A,&A);CHKERRQ(ierr);
ierr = PSSetDimensions(eps->ps,ld,0,k);CHKERRQ(ierr);
/* Normalize u and append it to V */
ierr = VecAXPBY(eps->V[sr->nS],1.0/sr->beta,0.0,eps->work[0]);CHKERRQ(ierr);
}
eps->nconv = 0;
}else sr->sPres = PETSC_NULL;
PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "EPSUpdateShiftRKS"
static PetscErrorCode EPSUpdateShiftRKS(PS ps,PetscReal sigma1,PetscReal sigma2)
{
#if defined(PETSC_MISSING_LAPACK_GEQRF) || defined(SLEPC_MISSING_LAPACK_ORGQR)
PetscFunctionBegin;
SETERRQ(PETSC_COMM_SELF,PETSC_ERR_SUP,"GEQRF/ORGQR - Lapack routine is unavailable.");
#else
PetscErrorCode ierr;
PetscInt i,j,l,ld;
PetscScalar *Q,*A,*tau,*R,*work,alpha;
PetscBLASInt n1,n0,ld_,lwork,info;
PetscFunctionBegin;
ierr = PSGetDimensions(ps,PETSC_NULL,PETSC_NULL,&l);
ierr = PSGetLeadingDimension(ps,&ld);CHKERRQ(ierr);
ierr = PSAllocateWork_Private(ps,ld*ld,0,0);CHKERRQ(ierr);
tau = ps->work;
work = tau + ld;
lwork = PetscBLASIntCast(ld*(ld-1));
ierr = PSAllocateMat_Private(ps,PS_MAT_W);CHKERRQ(ierr);
ierr = PSGetArray(ps,PS_MAT_W,&R);CHKERRQ(ierr);
ierr = PSGetArray(ps,PS_MAT_A,&A);CHKERRQ(ierr);
ierr = PSGetArray(ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
ierr = PetscMemzero(Q,ld*ld*sizeof(PetscScalar));CHKERRQ(ierr);
ierr = PetscMemzero(R,ld*ld*sizeof(PetscScalar));CHKERRQ(ierr);
for (i=0;i<l;i++){
Q[i+i*ld] = 1.0+(sigma1-sigma2)*A[i+i*ld];
Q[l+i*ld] = (sigma1-sigma2)*A[l+i*ld];
}
/* Compute qr */
ld_ = PetscBLASIntCast(ld);
n1 = PetscBLASIntCast(l+1);
n0 = PetscBLASIntCast(l);
ierr = PetscFPTrapPush(PETSC_FP_TRAP_OFF);CHKERRQ(ierr);
LAPACKgeqrf_(&n1,&n0,Q,&ld_,tau,work,&lwork,&info);
if (info) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in Lapack xGEQRF %d",info);
/* Copying R from Q */
for (j=0;j<l;j++)
for(i=0;i<=j;i++)
R[i+j*ld]=Q[i+j*ld];
/* Compute the orthogonal matrix in Q */
LAPACKorgqr_(&n1,&n1,&n0,Q,&ld_,tau,work,&lwork,&info);
if (info) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_LIB,"Error in Lapack xORGQR %d",info);
ierr = PetscFPTrapPop();CHKERRQ(ierr);
/* Compute the updated matrix of projected problem */
for(j=0;j<l;j++){
for(i=0;i<l+1;i++)
A[j*ld+i]=Q[i*ld+j];
}
alpha = -1.0/(sigma1-sigma2);
BLAStrsm_("R","U","N","N",&n1,&n0,&alpha,R,&ld_,A,&ld_);
for(i=0;i<l;i++)
A[ld*i+i]-=alpha;
ierr = PSRestoreArray(ps,PS_MAT_A,&A);CHKERRQ(ierr);
ierr = PSRestoreArray(ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
ierr = PSRestoreArray(ps,PS_MAT_W,&R);CHKERRQ(ierr);
ierr = PSSetState(ps,PS_STATE_RAW);CHKERRQ(ierr);
ierr = PSSetCompact(ps,PETSC_FALSE);CHKERRQ(ierr);
PetscFunctionReturn(0);
#endif
}
/*
Symmetric KrylovSchur adapted to spectrum slicing:
Allows searching an specific amount of eigenvalues in the subintervals left and right.
Returns whether the search has succeeded
*/
#undef __FUNCT__
#define __FUNCT__ "EPSKrylovSchur_Slice"
static PetscErrorCode EPSKrylovSchur_Slice(EPS eps)
{
PetscErrorCode ierr;
PetscInt i,conv,k,l,ld,nv,m,*iwork,p,j;
Vec u=eps->work[0];
PetscScalar *Q,*A,nu,rtmp,alpha;
PetscReal *a,*b,beta;
PetscBool breakdown;
PetscInt count0,count1;
PetscReal lambda;
shift sPres;
PetscBool complIterating,iscayley;
PetscBool sch0,sch1;
PetscInt iterCompl=0,n0,n1,aux,auxc;
SR sr;
PetscFunctionBegin;
/* Spectrum slicing data */
sr = (SR)eps->data;
sPres = sr->sPres;
complIterating =PETSC_FALSE;
sch1 = sch0 = PETSC_TRUE;
ierr = PSGetLeadingDimension(eps->ps,&ld);CHKERRQ(ierr);
ierr = PetscMalloc(2*ld*sizeof(PetscInt),&iwork);CHKERRQ(ierr);
count0=0;count1=0; /* Found on both sides */
/* filling in values for the monitor */
if(eps->numbermonitors >0){
ierr = PetscTypeCompare((PetscObject)eps->OP,STCAYLEY,&iscayley);CHKERRQ(ierr);
if(iscayley){
ierr = STCayleyGetAntishift(eps->OP,&nu);CHKERRQ(ierr);
for(i=0;i<sr->indexEig;i++){
sr->monit[i]=(nu + sr->eig[i])/(sr->eig[i] - sPres->value);
}
}else{
for(i=0;i<sr->indexEig;i++){
sr->monit[i]=1.0/(sr->eig[i] - sPres->value);
}
}
}
if(sr->nS > 0 && (sPres->neighb[0] == sr->sPrev || sPres->neighb[1] == sr->sPrev) ){
/* Rational Krylov */
ierr = EPSUpdateShiftRKS(eps->ps,sr->sPrev->value,sPres->value);CHKERRQ(ierr);
/* Update vectors */
ierr = PSGetArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
ierr = PSGetDimensions(eps->ps,PETSC_NULL,PETSC_NULL,&l);CHKERRQ(ierr);
ierr = SlepcUpdateVectors(l+1,eps->V,0,l+1,Q,ld,PETSC_FALSE);CHKERRQ(ierr);
ierr = PSRestoreArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
}else{
/* Get the starting Lanczos vector */
ierr = EPSGetStartVector(eps,0,eps->V[0],PETSC_NULL);CHKERRQ(ierr);
l = 0;
}
/* Restart loop */
while (eps->reason == EPS_CONVERGED_ITERATING) {
eps->its++; sr->itsKs++;
/* Compute an nv-step Lanczos factorization */
m = PetscMin(eps->nconv+eps->mpd,eps->ncv);
ierr = PSGetArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
b = a + ld;
ierr = EPSFullLanczos(eps,a+l,b+l,eps->V,eps->nconv+l,&m,u,&breakdown);CHKERRQ(ierr);
if(breakdown){/* explicit purification*/
sPres->expf = PETSC_TRUE;
}
nv = m - eps->nconv;
beta = b[nv-1];
ierr = PSRestoreArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
ierr = PSSetDimensions(eps->ps,nv,0,l);CHKERRQ(ierr);
if (l==0) {
ierr = PSSetState(eps->ps,PS_STATE_INTERMEDIATE);CHKERRQ(ierr);
} else {
ierr = PSSetState(eps->ps,PS_STATE_RAW);CHKERRQ(ierr);
}
/* Solve projected problem and compute residual norm estimates */
if(eps->its == 1 && l > 0){/* After rational update */
ierr = PSGetArray(eps->ps,PS_MAT_A,&A);CHKERRQ(ierr);
ierr = PSGetArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
b = a + ld;
A[l*ld+l-1] = A[(l-1)*ld+l];
A[l*ld+l] = a[l];
for(j=l+1; j< nv; j++){
A[j*ld+j] = a[j];
A[j*ld+j-1] = b[j-1] ;
A[(j-1)*ld+j] = b[j-1];
}
ierr = PSRestoreArray(eps->ps,PS_MAT_A,&A);CHKERRQ(ierr);
ierr = PSRestoreArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
ierr = PSSolve(eps->ps,eps->eigr+eps->nconv,PETSC_NULL);CHKERRQ(ierr);
}else{/* Restart */
ierr = PSSolve(eps->ps,eps->eigr+eps->nconv,PETSC_NULL);CHKERRQ(ierr);
}
ierr = PSSort(eps->ps,eps->eigr+eps->nconv,PETSC_NULL,eps->which_func,eps->which_ctx);CHKERRQ(ierr);
/* Residual */
ierr = PSGetArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
ierr = EPSKrylovConvergence(eps,PETSC_TRUE,PETSC_TRUE,eps->nconv,nv,PETSC_NULL,ld,Q,ld,eps->V+eps->nconv,nv,beta,1.0,&k,PETSC_NULL);CHKERRQ(ierr);
/* Check convergence */
ierr = PSGetArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
b = a + ld;
conv=k=j=0;
for(i=0;i<nv;i++)if(eps->errest[eps->nconv+i] < eps->tol)conv++;
for(i=0;i<nv;i++){
if(eps->errest[eps->nconv+i] < eps->tol){
iwork[j++]=i;
}else iwork[conv+k++]=i;
}
for(i=0;i<nv;i++){
a[i]=PetscRealPart(eps->eigr[eps->nconv+i]);
b[i]=eps->errest[eps->nconv+i];
}
for(i=0;i<nv;i++){
eps->eigr[eps->nconv+i] = a[iwork[i]];
eps->errest[eps->nconv+i] = b[iwork[i]];
}
for( i=0;i<nv;i++){
p=iwork[i];
if(p!=i){
j=i+1;
while(iwork[j]!=i)j++;
iwork[j]=p;iwork[i]=i;
for(k=0;k<nv;k++){
rtmp=Q[k+p*ld];Q[k+p*ld]=Q[k+i*ld];Q[k+i*ld]=rtmp;
}
}
}
k=eps->nconv+conv;
ierr = PSRestoreArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
ierr = PSRestoreArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
/* Checking values obtained for completing */
for(i=0;i<k;i++){
sr->back[i]=eps->eigr[i];
}
ierr = STBackTransform(eps->OP,k,sr->back,eps->eigi);CHKERRQ(ierr);
count0=count1=0;
for(i=0;i<k;i++){
lambda = PetscRealPart(sr->back[i]);
if( ((sr->dir)*(sPres->value - lambda) > 0) && ((sr->dir)*(lambda - sPres->ext[0]) > 0))count0++;
if( ((sr->dir)*(lambda - sPres->value) > 0) && ((sr->dir)*(sPres->ext[1] - lambda) > 0))count1++;
}
/* Checks completion */
if( (!sch0||count0 >= sPres->nsch[0]) && (!sch1 ||count1 >= sPres->nsch[1]) ) {
eps->reason = EPS_CONVERGED_TOL;
}else {
if(!complIterating && eps->its >= eps->max_it) eps->reason = EPS_DIVERGED_ITS;
if(complIterating){
if(--iterCompl <= 0) eps->reason = EPS_DIVERGED_ITS;
}else if (k >= eps->nev) {
n0 = sPres->nsch[0]-count0;
n1 = sPres->nsch[1]-count1;
if( sr->iterCompl>0 && ( (n0>0 && n0<= sr->nMAXCompl)||(n1>0&&n1<=sr->nMAXCompl) )){
/* Iterating for completion*/
complIterating = PETSC_TRUE;
if(n0 >sr->nMAXCompl)sch0 = PETSC_FALSE;
if(n1 >sr->nMAXCompl)sch1 = PETSC_FALSE;
iterCompl = sr->iterCompl;
}else eps->reason = EPS_CONVERGED_TOL;
}
}
/* Update l */
if(eps->reason == EPS_CONVERGED_ITERATING )l = (eps->nconv+nv-k)/2;
else l=eps->nconv+nv-k;
if(breakdown)l=0;
if (eps->reason == EPS_CONVERGED_ITERATING) {
if (breakdown) {
/* Start a new Lanczos factorization */
ierr = PetscInfo2(eps,"Breakdown in Krylov-Schur method (it=%D norm=%G)\n",eps->its,beta);CHKERRQ(ierr);
ierr = EPSGetStartVector(eps,k,eps->V[k],&breakdown);CHKERRQ(ierr);
if (breakdown) {
eps->reason = EPS_DIVERGED_BREAKDOWN;
ierr = PetscInfo(eps,"Unable to generate more start vectors\n");CHKERRQ(ierr);
}
} else {
/* Prepare the Rayleigh quotient for restart */
ierr = PSGetArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
ierr = PSGetArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
b = a + ld;
for (i=0;i<l;i++) {
a[i] = PetscRealPart(eps->eigr[i+k]);
b[i] = PetscRealPart(Q[nv-1+(i+k-eps->nconv)*ld]*beta);
}
ierr = PSRestoreArrayReal(eps->ps,PS_MAT_T,&a);CHKERRQ(ierr);
ierr = PSRestoreArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
}
}
/* Update the corresponding vectors V(:,idx) = V*Q(:,idx) */
ierr = PSGetArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
ierr = SlepcUpdateVectors(nv,eps->V+eps->nconv,0,k+l-eps->nconv,Q,ld,PETSC_FALSE);CHKERRQ(ierr);
/* Purification */
if(!sPres->expf){/* u not saved if breakdown */
for(i=eps->nconv; i<k;i++){
alpha = (Q[nv-1+(i-eps->nconv)*ld])/PetscRealPart(eps->eigr[i]);
ierr = VecAXPY(eps->V[i], alpha, u);CHKERRQ(ierr);
}
}
ierr = PSRestoreArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
/* Normalize u and append it to V */
if ( eps->reason == EPS_CONVERGED_ITERATING && !breakdown) {
ierr = VecAXPBY(eps->V[k+l],1.0/beta,0.0,u);CHKERRQ(ierr);
}
/* Monitor */
if(eps->numbermonitors >0){
aux = auxc = 0;
for(i=0;i<nv+eps->nconv;i++){
sr->back[i]=eps->eigr[i];
}
ierr = STBackTransform(eps->OP,nv+eps->nconv,sr->back,eps->eigi);CHKERRQ(ierr);
for(i=0;i<nv+eps->nconv;i++){
lambda = PetscRealPart(sr->back[i]);
if( ((sr->dir)*(lambda - sPres->ext[0]) > 0)&& ((sr->dir)*(sPres->ext[1] - lambda) > 0)){
sr->monit[sr->indexEig+aux]=eps->eigr[i];
sr->errest[sr->indexEig+aux]=eps->errest[i];
aux++;
if(eps->errest[i] < eps->tol)auxc++;
}
}
ierr = EPSMonitor(eps,eps->its,auxc+sr->indexEig,sr->monit,sr->eigi,sr->errest,sr->indexEig+aux);CHKERRQ(ierr);
}
conv = k - eps->nconv;
eps->nconv = k;
if(eps->reason != EPS_CONVERGED_ITERATING){
/* Store approximated values for next shift */
ierr = PSGetArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
sr->nS = l;
for (i=0;i<l;i++) {
sr->S[i] = eps->eigr[i+k];/* Diagonal elements */
sr->S[i+l] = Q[nv-1+(i+conv)*ld]*beta; /* Out of diagonal elements */
}
sr->beta = beta;
ierr = PSRestoreArray(eps->ps,PS_MAT_Q,&Q);CHKERRQ(ierr);
}
}
/* Check for completion */
for(i=0;i< eps->nconv; i++){
if( (sr->dir)*PetscRealPart(eps->eigr[i])>0 )sPres->nconv[1]++;
else sPres->nconv[0]++;
}
sPres->comp[0] = (count0 >= sPres->nsch[0])?PETSC_TRUE:PETSC_FALSE;
sPres->comp[1] = (count1 >= sPres->nsch[1])?PETSC_TRUE:PETSC_FALSE;
if(count0 > sPres->nsch[0] || count1 > sPres->nsch[1])SETERRQ(((PetscObject)eps)->comm,1,"Unexpected error in Spectrum Slicing!\nMismatch between number of values found and information from inertia");
ierr = PetscFree(iwork);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/*
Obtains value of subsequent shift
*/
#undef __FUNCT__
#define __FUNCT__ "EPSGetNewShiftValue"
static PetscErrorCode EPSGetNewShiftValue(EPS eps,PetscInt side,PetscReal *newS)
{
PetscReal lambda,d_prev;
PetscInt i,idxP;
SR sr;
shift sPres,s;
PetscFunctionBegin;
sr = (SR)eps->data;
sPres = sr->sPres;
if( sPres->neighb[side]){
/* Completing a previous interval */
if(!sPres->neighb[side]->neighb[side] && sPres->neighb[side]->nconv[side]==0){ /* One of the ends might be too far from eigenvalues */
if(side) *newS = (sPres->value + PetscRealPart(sr->eig[sr->perm[sr->indexEig-1]]))/2;
else *newS = (sPres->value + PetscRealPart(sr->eig[sr->perm[0]]))/2;
}else *newS=(sPres->value + sPres->neighb[side]->value)/2;
}else{ /* (Only for side=1). Creating a new interval. */
if(sPres->neigs==0){/* No value has been accepted*/
if(sPres->neighb[0]){
/* Multiplying by 10 the previous distance */
*newS = sPres->value + 10*(sr->dir)*PetscAbsReal(sPres->value - sPres->neighb[0]->value);
sr->nleap++;
/* Stops when the interval is open and no values are found in the last 5 shifts (there might be infinite eigenvalues) */
if( !sr->hasEnd && sr->nleap > 5)SETERRQ(((PetscObject)eps)->comm,1,"Unable to compute the wanted eigenvalues with open interval");
}else {/* First shift */
if(eps->nconv != 0){
/* Unaccepted values give information for next shift */
idxP=0;/* Number of values left from shift */
for(i=0;i<eps->nconv;i++){
lambda = PetscRealPart(eps->eigr[i]);
if( (sr->dir)*(lambda - sPres->value) <0)idxP++;
else break;
}
/* Avoiding subtraction of eigenvalues (might be the same).*/
if(idxP>0){
d_prev = PetscAbsReal(sPres->value - PetscRealPart(eps->eigr[0]))/(idxP+0.3);
}else {
d_prev = PetscAbsReal(sPres->value - PetscRealPart(eps->eigr[eps->nconv-1]))/(eps->nconv+0.3);
}
*newS = sPres->value + ((sr->dir)*d_prev*eps->nev)/2;
}else{/* No values found, no information for next shift */
SETERRQ(((PetscObject)eps)->comm,1,"First shift renders no information");
}
}
}else{/* Accepted values found */
sr->nleap = 0;
/* Average distance of values in previous subinterval */
s = sPres->neighb[0];
while(s && PetscAbs(s->inertia - sPres->inertia)==0){
s = s->neighb[0];/* Looking for previous shifts with eigenvalues within */
}
if(s){
d_prev = PetscAbsReal( (sPres->value - s->value)/(sPres->inertia - s->inertia));
}else{/* First shift. Average distance obtained with values in this shift */
/* first shift might be too far from first wanted eigenvalue (no values found outside the interval)*/
if( (sr->dir)*(PetscRealPart(sr->eig[0])-sPres->value)>0 && PetscAbsReal( (PetscRealPart(sr->eig[sr->indexEig-1]) - PetscRealPart(sr->eig[0]))/PetscRealPart(sr->eig[0])) > PetscSqrtReal(eps->tol) ){
d_prev = PetscAbsReal( (PetscRealPart(sr->eig[sr->indexEig-1]) - PetscRealPart(sr->eig[0])))/(sPres->neigs+0.3);
}else{
d_prev = PetscAbsReal( PetscRealPart(sr->eig[sr->indexEig-1]) - sPres->value)/(sPres->neigs+0.3);
}
}
/* Average distance is used for next shift by adding it to value on the right or to shift */
if( (sr->dir)*(PetscRealPart(sr->eig[sPres->index + sPres->neigs -1]) - sPres->value) >0){
*newS = PetscRealPart(sr->eig[sPres->index + sPres->neigs -1])+ ((sr->dir)*d_prev*(eps->nev))/2;
}else{/* Last accepted value is on the left of shift. Adding to shift */
*newS = sPres->value + ((sr->dir)*d_prev*(eps->nev))/2;
}
}
/* End of interval can not be surpassed */
if((sr->dir)*( sr->int1 - *newS) < 0) *newS = sr->int1;
}/* of neighb[side]==null */
PetscFunctionReturn(0);
}
/*
Function for sorting an array of real values
*/
#undef __FUNCT__
#define __FUNCT__ "sortRealEigenvalues"
static PetscErrorCode sortRealEigenvalues(PetscScalar *r,PetscInt *perm,PetscInt nr,PetscBool prev,PetscInt dir)
{
PetscReal re;
PetscInt i,j,tmp;
PetscFunctionBegin;
if(!prev) for (i=0; i < nr; i++) { perm[i] = i; }
/* Insertion sort */
for (i=1; i < nr; i++) {
re = PetscRealPart(r[perm[i]]);
j = i-1;
while ( j>=0 && dir*(re - PetscRealPart(r[perm[j]])) <= 0 ) {
tmp = perm[j]; perm[j] = perm[j+1]; perm[j+1] = tmp; j--;
}
}
PetscFunctionReturn(0);
}
/* Stores the pairs obtained since the last shift in the global arrays */
#undef __FUNCT__
#define __FUNCT__ "EPSStoreEigenpairs"
PetscErrorCode EPSStoreEigenpairs(EPS eps)
{
PetscErrorCode ierr;
PetscReal lambda,err,norm;
PetscInt i,count;
PetscBool iscayley;
SR sr;
shift sPres;
PetscFunctionBegin;
sr = (SR)(eps->data);
sPres = sr->sPres;
sPres->index = sr->indexEig;
count = sr->indexEig;
/* Back-transform */
ierr = EPSBackTransform_Default(eps);CHKERRQ(ierr);
ierr = PetscTypeCompare((PetscObject)eps->OP,STCAYLEY,&iscayley);CHKERRQ(ierr);
/* Sort eigenvalues */
ierr = sortRealEigenvalues(eps->eigr,eps->perm,eps->nconv,PETSC_FALSE,sr->dir);
/* Values stored in global array */
for( i=0; i < eps->nconv ;i++ ){
lambda = PetscRealPart(eps->eigr[eps->perm[i]]);
err = eps->errest[eps->perm[i]];
if( (sr->dir)*(lambda - sPres->ext[0]) > 0 && (sr->dir)*(sPres->ext[1] - lambda) > 0 ){/* Valid value */
if(count>=sr->numEigs){/* Error found */
SETERRQ(((PetscObject)eps)->comm,1,"Unexpected error in Spectrum Slicing!");
}
sr->eig[count] = lambda;
sr->errest[count] = err;
/* Unlikely explicit purification */
if (sPres->expf && eps->isgeneralized && !iscayley){
ierr = STApply(eps->OP,eps->V[eps->perm[i]],sr->V[count]);CHKERRQ(ierr);
ierr = IPNorm(eps->ip,sr->V[count],&norm);CHKERRQ(ierr);
ierr = VecScale(sr->V[count],1.0/norm);CHKERRQ(ierr);
}else{
ierr = VecCopy(eps->V[eps->perm[i]], sr->V[count]);CHKERRQ(ierr);
}
count++;
}
}
sPres->neigs = count - sr->indexEig;
sr->indexEig = count;
/* Global ordering array updating */
ierr = sortRealEigenvalues(sr->eig,sr->perm,count,PETSC_TRUE,sr->dir);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "EPSLookForDeflation"
PetscErrorCode EPSLookForDeflation(EPS eps)
{
PetscReal val;
PetscInt i,count0=0,count1=0;
shift sPres;
PetscInt ini,fin,k,idx0,idx1;
SR sr;
PetscFunctionBegin;
sr = (SR)(eps->data);
sPres = sr->sPres;
if(sPres->neighb[0]) ini = (sr->dir)*(sPres->neighb[0]->inertia - sr->inertia0);
else ini = 0;
fin = sr->indexEig;
/* Selection of ends for searching new values */
if(!sPres->neighb[0]) sPres->ext[0] = sr->int0;/* First shift */
else sPres->ext[0] = sPres->neighb[0]->value;
if(!sPres->neighb[1]) {
if(sr->hasEnd) sPres->ext[1] = sr->int1;
else sPres->ext[1] = (sr->dir > 0)?PETSC_MAX_REAL:PETSC_MIN_REAL;
}else sPres->ext[1] = sPres->neighb[1]->value;
/* Selection of values between right and left ends */
for(i=ini;i<fin;i++){
val=PetscRealPart(sr->eig[sr->perm[i]]);
/* Values to the right of left shift */
if( (sr->dir)*(val - sPres->ext[1]) < 0 ){
if((sr->dir)*(val - sPres->value) < 0)count0++;
else count1++;
}else break;
}
/* The number of values on each side are found */
if(sPres->neighb[0]){
sPres->nsch[0] = (sr->dir)*(sPres->inertia - sPres->neighb[0]->inertia)-count0;
if(sPres->nsch[0]<0)SETERRQ(((PetscObject)eps)->comm,1,"Unexpected error in Spectrum Slicing!\nMismatch between number of values found and information from inertia");
}else sPres->nsch[0] = 0;
if(sPres->neighb[1]){
sPres->nsch[1] = (sr->dir)*(sPres->neighb[1]->inertia - sPres->inertia) - count1;
if(sPres->nsch[1]<0)SETERRQ(((PetscObject)eps)->comm,1,"Unexpected error in Spectrum Slicing!\nMismatch between number of values found and information from inertia");
}else sPres->nsch[1] = (sr->dir)*(sr->inertia1 - sPres->inertia);
/* Completing vector of indexes for deflation */
idx0 = ini;
idx1 = ini+count0+count1;
k=0;
for(i=idx0;i<idx1;i++)sr->idxDef[k++]=sr->perm[i];
for(i=0;i<k;i++)sr->VDef[i]=sr->V[sr->idxDef[i]];
eps->DS = sr->VDef;
eps->nds = k;
PetscFunctionReturn(0);
}
#undef __FUNCT__
#define __FUNCT__ "EPSSolve_KrylovSchur_Slice"
PetscErrorCode EPSSolve_KrylovSchur_Slice(EPS eps)
{
PetscErrorCode ierr;
PetscInt i,lds;
PetscReal newS;
KSP ksp;
PC pc;
Mat F;
PetscReal *errest_left;
Vec t;
SR sr;
shift s;
PetscFunctionBegin;
#if defined(PETSC_USE_COMPLEX)
SETERRQ(((PetscObject)eps)->comm,PETSC_ERR_SUP,"Spectrum slicing not supported in complex scalars");
#endif
ierr = PetscMalloc(sizeof(struct _n_SR),&sr);CHKERRQ(ierr);
eps->data = sr;
sr->itsKs = 0;
sr->nleap = 0;
sr->nMAXCompl = eps->nev/4;
sr->iterCompl = eps->max_it/4;
sr->sPres = PETSC_NULL;
sr->nS = 0;
lds = PetscMin(eps->mpd,eps->ncv);
/* Checking presence of ends and finding direction */
if( eps->inta > PETSC_MIN_REAL){
sr->int0 = eps->inta;
sr->int1 = eps->intb;
sr->dir = 1;
if(eps->intb >= PETSC_MAX_REAL){ /* Right-open interval */
sr->hasEnd = PETSC_FALSE;
sr->inertia1 = eps->n;
}else sr->hasEnd = PETSC_TRUE;
}else{ /* Left-open interval */
sr->int0 = eps->intb;
sr->int1 = eps->inta;
sr->dir = -1;
sr->hasEnd = PETSC_FALSE;
sr->inertia1 = 0;
}
/* Array of pending shifts */
sr->maxPend = 100;/* Initial size */
ierr = PetscMalloc((sr->maxPend)*sizeof(shift),&sr->pending);CHKERRQ(ierr);
if(sr->hasEnd){
ierr = STGetKSP(eps->OP, &ksp);CHKERRQ(ierr);
ierr = KSPGetPC(ksp, &pc);CHKERRQ(ierr);
ierr = PCFactorGetMatrix(pc,&F);CHKERRQ(ierr);
/* Not looking for values in b (just inertia).*/
ierr = MatGetInertia(F,&sr->inertia1,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
ierr = PCReset(pc);CHKERRQ(ierr); /* avoiding memory leak */
}
sr->nPend = 0;
ierr = EPSCreateShift(eps,sr->int0,PETSC_NULL,PETSC_NULL);CHKERRQ(ierr);
ierr = EPSExtractShift(eps);
sr->s0 = sr->sPres;
sr->inertia0 = sr->s0->inertia;
sr->numEigs = (sr->dir)*(sr->inertia1 - sr->inertia0);
sr->indexEig = 0;
/* Only with eigenvalues present in the interval ...*/
if(sr->numEigs==0){
eps->reason = EPS_CONVERGED_TOL;
ierr = PetscFree(sr->s0);CHKERRQ(ierr);
ierr = PetscFree(sr->pending);CHKERRQ(ierr);
ierr = PetscFree(sr);CHKERRQ(ierr);
PetscFunctionReturn(0);
}
/* Memory reservation for eig, V and perm */
ierr = PetscMalloc(lds*lds*sizeof(PetscScalar),&sr->S);CHKERRQ(ierr);
ierr = PetscMemzero(sr->S,lds*lds*sizeof(PetscScalar));CHKERRQ(ierr);
ierr = PetscMalloc((sr->numEigs)*sizeof(PetscScalar),&sr->eig);CHKERRQ(ierr);
ierr = PetscMalloc((sr->numEigs)*sizeof(PetscScalar),&sr->eigi);CHKERRQ(ierr);
ierr = PetscMalloc((sr->numEigs+eps->ncv) *sizeof(PetscReal),&sr->errest);CHKERRQ(ierr);
ierr = PetscMalloc((sr->numEigs+eps->ncv)*sizeof(PetscReal),&errest_left);CHKERRQ(ierr);
ierr = PetscMalloc((sr->numEigs+eps->ncv)*sizeof(PetscScalar),&sr->monit);CHKERRQ(ierr);
ierr = PetscMalloc((eps->ncv)*sizeof(PetscScalar),&sr->back);CHKERRQ(ierr);
for(i=0;i<sr->numEigs;i++){sr->eigi[i]=0;sr->eig[i] = 0;}
for(i=0;i<sr->numEigs+eps->ncv;i++){errest_left[i]=0;sr->errest[i]=0;sr->monit[i]=0;}
ierr = VecCreateMPI(((PetscObject)eps)->comm,eps->nloc,PETSC_DECIDE,&t);CHKERRQ(ierr);
ierr = VecDuplicateVecs(t,sr->numEigs,&sr->V);CHKERRQ(ierr);
ierr = VecDestroy(&t);CHKERRQ(ierr);
/* Vector for maintaining order of eigenvalues */
ierr = PetscMalloc((sr->numEigs)*sizeof(PetscInt),&sr->perm);CHKERRQ(ierr);
for(i=0;i< sr->numEigs;i++)sr->perm[i]=i;
/* Vectors for deflation */
ierr = PetscMalloc((sr->numEigs)*sizeof(PetscInt),&sr->idxDef);CHKERRQ(ierr);
ierr = PetscMalloc((sr->numEigs)*sizeof(Vec),&sr->VDef);CHKERRQ(ierr);
sr->indexEig = 0;
/* Main loop */
while(sr->sPres){
/* Search for deflation */
ierr = EPSLookForDeflation(eps);CHKERRQ(ierr);
/* KrylovSchur */
ierr = EPSKrylovSchur_Slice(eps);CHKERRQ(ierr);
ierr = EPSStoreEigenpairs(eps);CHKERRQ(ierr);
/* Select new shift */
if(!sr->sPres->comp[1]){
ierr = EPSGetNewShiftValue(eps,1,&newS);CHKERRQ(ierr);
ierr = EPSCreateShift(eps,newS,sr->sPres,sr->sPres->neighb[1]);
}
if(!sr->sPres->comp[0]){
/* Completing earlier interval */
ierr = EPSGetNewShiftValue(eps,0,&newS);CHKERRQ(ierr);
ierr = EPSCreateShift(eps,newS,sr->sPres->neighb[0],sr->sPres);
}
/* Preparing for a new search of values */
ierr = EPSExtractShift(eps);CHKERRQ(ierr);
}
/* Updating eps values prior to exit */
ierr = VecDestroyVecs(eps->allocated_ncv,&eps->V);CHKERRQ(ierr);
eps->V = sr->V;
ierr = PetscFree(sr->S);CHKERRQ(ierr);
ierr = PetscFree(eps->eigr);CHKERRQ(ierr);
ierr = PetscFree(eps->eigi);CHKERRQ(ierr);
ierr = PetscFree(eps->errest);CHKERRQ(ierr);
ierr = PetscFree(eps->errest_left);CHKERRQ(ierr);
ierr = PetscFree(eps->perm);CHKERRQ(ierr);
eps->eigr = sr->eig;
eps->eigi = sr->eigi;
eps->errest = sr->errest;
eps->errest_left = errest_left;
eps->perm = sr->perm;
eps->ncv = eps->allocated_ncv = sr->numEigs;
eps->nconv = sr->indexEig;
eps->reason = EPS_CONVERGED_TOL;
eps->its = sr->itsKs;
eps->nds = 0;
eps->DS = PETSC_NULL;
eps->evecsavailable = PETSC_TRUE;
ierr = PetscFree(sr->VDef);CHKERRQ(ierr);
ierr = PetscFree(sr->idxDef);CHKERRQ(ierr);
ierr = PetscFree(sr->pending);CHKERRQ(ierr);
ierr = PetscFree(sr->monit);CHKERRQ(ierr);
ierr = PetscFree(sr->back);CHKERRQ(ierr);
/* Reviewing list of shifts to free memory */
s = sr->s0;
if(s){
while(s->neighb[1]){
s = s->neighb[1];
ierr = PetscFree(s->neighb[0]);CHKERRQ(ierr);
}
ierr = PetscFree(s);CHKERRQ(ierr);
}
ierr = PetscFree(sr);CHKERRQ(ierr);
PetscFunctionReturn(0);
}