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paboyle 2018-01-15 00:21:27 +00:00
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652
lib/algorithms/approx/Chebyshev.h
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@ -1,4 +1,4 @@
/************************************************************************************* /*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid Grid physics library, www.github.com/paboyle/Grid
@ -25,14 +25,14 @@ Author: Christoph Lehner <clehner@bnl.gov>
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
See the full license in the file "LICENSE" in the top level distribution directory See the full license in the file "LICENSE" in the top level distribution directory
*************************************************************************************/ *************************************************************************************/
/* END LEGAL */ /* END LEGAL */
#ifndef GRID_CHEBYSHEV_H #ifndef GRID_CHEBYSHEV_H
#define GRID_CHEBYSHEV_H #define GRID_CHEBYSHEV_H
#include <Grid/algorithms/LinearOperator.h> #include <Grid/algorithms/LinearOperator.h>
namespace Grid { NAMESPACE_BEGIN(Grid);
struct ChebyParams : Serializable { struct ChebyParams : Serializable {
GRID_SERIALIZABLE_CLASS_MEMBERS(ChebyParams, GRID_SERIALIZABLE_CLASS_MEMBERS(ChebyParams,
@ -41,337 +41,337 @@ struct ChebyParams : Serializable {
int, Npoly); int, Npoly);
}; };
//////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////////////////
// Generic Chebyshev approximations // Generic Chebyshev approximations
//////////////////////////////////////////////////////////////////////////////////////////// ////////////////////////////////////////////////////////////////////////////////////////////
template<class Field> template<class Field>
class Chebyshev : public OperatorFunction<Field> { class Chebyshev : public OperatorFunction<Field> {
private: private:
std::vector<RealD> Coeffs; std::vector<RealD> Coeffs;
int order; int order;
RealD hi; RealD hi;
RealD lo; RealD lo;
public: public:
void csv(std::ostream &out){ void csv(std::ostream &out){
RealD diff = hi-lo; RealD diff = hi-lo;
RealD delta = (hi-lo)*1.0e-9; RealD delta = (hi-lo)*1.0e-9;
for (RealD x=lo; x<hi; x+=delta) { for (RealD x=lo; x<hi; x+=delta) {
delta*=1.1; delta*=1.1;
RealD f = approx(x); RealD f = approx(x);
out<< x<<" "<<f<<std::endl; out<< x<<" "<<f<<std::endl;
}
return;
} }
return;
}
// Convenience for plotting the approximation // Convenience for plotting the approximation
void PlotApprox(std::ostream &out) { void PlotApprox(std::ostream &out) {
out<<"Polynomial approx ["<<lo<<","<<hi<<"]"<<std::endl; out<<"Polynomial approx ["<<lo<<","<<hi<<"]"<<std::endl;
for(RealD x=lo;x<hi;x+=(hi-lo)/50.0){ for(RealD x=lo;x<hi;x+=(hi-lo)/50.0){
out <<x<<"\t"<<approx(x)<<std::endl; out <<x<<"\t"<<approx(x)<<std::endl;
}
};
Chebyshev(){};
Chebyshev(ChebyParams p){ Init(p.alpha,p.beta,p.Npoly);};
Chebyshev(RealD _lo,RealD _hi,int _order, RealD (* func)(RealD) ) {Init(_lo,_hi,_order,func);};
Chebyshev(RealD _lo,RealD _hi,int _order) {Init(_lo,_hi,_order);};
////////////////////////////////////////////////////////////////////////////////////////////////////
// c.f. numerical recipes "chebft"/"chebev". This is sec 5.8 "Chebyshev approximation".
////////////////////////////////////////////////////////////////////////////////////////////////////
// CJ: the one we need for Lanczos
void Init(RealD _lo,RealD _hi,int _order)
{
lo=_lo;
hi=_hi;
order=_order;
if(order < 2) exit(-1);
Coeffs.resize(order);
Coeffs.assign(0.,order);
Coeffs[order-1] = 1.;
};
void Init(RealD _lo,RealD _hi,int _order, RealD (* func)(RealD))
{
lo=_lo;
hi=_hi;
order=_order;
if(order < 2) exit(-1);
Coeffs.resize(order);
for(int j=0;j<order;j++){
RealD s=0;
for(int k=0;k<order;k++){
RealD y=std::cos(M_PI*(k+0.5)/order);
RealD x=0.5*(y*(hi-lo)+(hi+lo));
RealD f=func(x);
s=s+f*std::cos( j*M_PI*(k+0.5)/order );
}
Coeffs[j] = s * 2.0/order;
}
};
void JacksonSmooth(void){
RealD M=order;
RealD alpha = M_PI/(M+2);
RealD lmax = std::cos(alpha);
RealD sumUsq =0;
std::vector<RealD> U(M);
std::vector<RealD> a(M);
std::vector<RealD> g(M);
for(int n=0;n<=M;n++){
U[n] = std::sin((n+1)*std::acos(lmax))/std::sin(std::acos(lmax));
sumUsq += U[n]*U[n];
}
sumUsq = std::sqrt(sumUsq);
for(int i=1;i<=M;i++){
a[i] = U[i]/sumUsq;
}
g[0] = 1.0;
for(int m=1;m<=M;m++){
g[m] = 0;
for(int i=0;i<=M-m;i++){
g[m]+= a[i]*a[m+i];
}
}
for(int m=1;m<=M;m++){
Coeffs[m]*=g[m];
}
}
RealD approx(RealD x) // Convenience for plotting the approximation
{
RealD Tn;
RealD Tnm;
RealD Tnp;
RealD y=( x-0.5*(hi+lo))/(0.5*(hi-lo));
RealD T0=1;
RealD T1=y;
RealD sum;
sum = 0.5*Coeffs[0]*T0;
sum+= Coeffs[1]*T1;
Tn =T1;
Tnm=T0;
for(int i=2;i<order;i++){
Tnp=2*y*Tn-Tnm;
Tnm=Tn;
Tn =Tnp;
sum+= Tn*Coeffs[i];
}
return sum;
};
RealD approxD(RealD x)
{
RealD Un;
RealD Unm;
RealD Unp;
RealD y=( x-0.5*(hi+lo))/(0.5*(hi-lo));
RealD U0=1;
RealD U1=2*y;
RealD sum;
sum = Coeffs[1]*U0;
sum+= Coeffs[2]*U1*2.0;
Un =U1;
Unm=U0;
for(int i=2;i<order-1;i++){
Unp=2*y*Un-Unm;
Unm=Un;
Un =Unp;
sum+= Un*Coeffs[i+1]*(i+1.0);
}
return sum/(0.5*(hi-lo));
};
RealD approxInv(RealD z, RealD x0, int maxiter, RealD resid) {
RealD x = x0;
RealD eps;
int i;
for (i=0;i<maxiter;i++) {
eps = approx(x) - z;
if (fabs(eps / z) < resid)
return x;
x = x - eps / approxD(x);
}
return std::numeric_limits<double>::quiet_NaN();
}
// Implement the required interface
void operator() (LinearOperatorBase<Field> &Linop, const Field &in, Field &out) {
GridBase *grid=in._grid;
// std::cout << "Chevyshef(): in._grid="<<in._grid<<std::endl;
//std::cout <<" Linop.Grid()="<<Linop.Grid()<<"Linop.RedBlackGrid()="<<Linop.RedBlackGrid()<<std::endl;
int vol=grid->gSites();
Field T0(grid); T0 = in;
Field T1(grid);
Field T2(grid);
Field y(grid);
Field *Tnm = &T0;
Field *Tn = &T1;
Field *Tnp = &T2;
// Tn=T1 = (xscale M + mscale)in
RealD xscale = 2.0/(hi-lo);
RealD mscale = -(hi+lo)/(hi-lo);
Linop.HermOp(T0,y);
T1=y*xscale+in*mscale;
// sum = .5 c[0] T0 + c[1] T1
out = (0.5*Coeffs[0])*T0 + Coeffs[1]*T1;
for(int n=2;n<order;n++){
Linop.HermOp(*Tn,y);
y=xscale*y+mscale*(*Tn);
*Tnp=2.0*y-(*Tnm);
out=out+Coeffs[n]* (*Tnp);
// Cycle pointers to avoid copies
Field *swizzle = Tnm;
Tnm =Tn;
Tn =Tnp;
Tnp =swizzle;
}
} }
}; };
Chebyshev(){};
Chebyshev(ChebyParams p){ Init(p.alpha,p.beta,p.Npoly);};
Chebyshev(RealD _lo,RealD _hi,int _order, RealD (* func)(RealD) ) {Init(_lo,_hi,_order,func);};
Chebyshev(RealD _lo,RealD _hi,int _order) {Init(_lo,_hi,_order);};
template<class Field> ////////////////////////////////////////////////////////////////////////////////////////////////////
class ChebyshevLanczos : public Chebyshev<Field> { // c.f. numerical recipes "chebft"/"chebev". This is sec 5.8 "Chebyshev approximation".
private: ////////////////////////////////////////////////////////////////////////////////////////////////////
std::vector<RealD> Coeffs; // CJ: the one we need for Lanczos
int order; void Init(RealD _lo,RealD _hi,int _order)
RealD alpha; {
RealD beta; lo=_lo;
RealD mu; hi=_hi;
order=_order;
if(order < 2) exit(-1);
Coeffs.resize(order);
Coeffs.assign(0.,order);
Coeffs[order-1] = 1.;
};
public: void Init(RealD _lo,RealD _hi,int _order, RealD (* func)(RealD))
ChebyshevLanczos(RealD _alpha,RealD _beta,RealD _mu,int _order) : {
lo=_lo;
hi=_hi;
order=_order;
if(order < 2) exit(-1);
Coeffs.resize(order);
for(int j=0;j<order;j++){
RealD s=0;
for(int k=0;k<order;k++){
RealD y=std::cos(M_PI*(k+0.5)/order);
RealD x=0.5*(y*(hi-lo)+(hi+lo));
RealD f=func(x);
s=s+f*std::cos( j*M_PI*(k+0.5)/order );
}
Coeffs[j] = s * 2.0/order;
}
};
void JacksonSmooth(void){
RealD M=order;
RealD alpha = M_PI/(M+2);
RealD lmax = std::cos(alpha);
RealD sumUsq =0;
std::vector<RealD> U(M);
std::vector<RealD> a(M);
std::vector<RealD> g(M);
for(int n=0;n<=M;n++){
U[n] = std::sin((n+1)*std::acos(lmax))/std::sin(std::acos(lmax));
sumUsq += U[n]*U[n];
}
sumUsq = std::sqrt(sumUsq);
for(int i=1;i<=M;i++){
a[i] = U[i]/sumUsq;
}
g[0] = 1.0;
for(int m=1;m<=M;m++){
g[m] = 0;
for(int i=0;i<=M-m;i++){
g[m]+= a[i]*a[m+i];
}
}
for(int m=1;m<=M;m++){
Coeffs[m]*=g[m];
}
}
RealD approx(RealD x) // Convenience for plotting the approximation
{
RealD Tn;
RealD Tnm;
RealD Tnp;
RealD y=( x-0.5*(hi+lo))/(0.5*(hi-lo));
RealD T0=1;
RealD T1=y;
RealD sum;
sum = 0.5*Coeffs[0]*T0;
sum+= Coeffs[1]*T1;
Tn =T1;
Tnm=T0;
for(int i=2;i<order;i++){
Tnp=2*y*Tn-Tnm;
Tnm=Tn;
Tn =Tnp;
sum+= Tn*Coeffs[i];
}
return sum;
};
RealD approxD(RealD x)
{
RealD Un;
RealD Unm;
RealD Unp;
RealD y=( x-0.5*(hi+lo))/(0.5*(hi-lo));
RealD U0=1;
RealD U1=2*y;
RealD sum;
sum = Coeffs[1]*U0;
sum+= Coeffs[2]*U1*2.0;
Un =U1;
Unm=U0;
for(int i=2;i<order-1;i++){
Unp=2*y*Un-Unm;
Unm=Un;
Un =Unp;
sum+= Un*Coeffs[i+1]*(i+1.0);
}
return sum/(0.5*(hi-lo));
};
RealD approxInv(RealD z, RealD x0, int maxiter, RealD resid) {
RealD x = x0;
RealD eps;
int i;
for (i=0;i<maxiter;i++) {
eps = approx(x) - z;
if (fabs(eps / z) < resid)
return x;
x = x - eps / approxD(x);
}
return std::numeric_limits<double>::quiet_NaN();
}
// Implement the required interface
void operator() (LinearOperatorBase<Field> &Linop, const Field &in, Field &out) {
GridBase *grid=in._grid;
// std::cout << "Chevyshef(): in._grid="<<in._grid<<std::endl;
//std::cout <<" Linop.Grid()="<<Linop.Grid()<<"Linop.RedBlackGrid()="<<Linop.RedBlackGrid()<<std::endl;
int vol=grid->gSites();
Field T0(grid); T0 = in;
Field T1(grid);
Field T2(grid);
Field y(grid);
Field *Tnm = &T0;
Field *Tn = &T1;
Field *Tnp = &T2;
// Tn=T1 = (xscale M + mscale)in
RealD xscale = 2.0/(hi-lo);
RealD mscale = -(hi+lo)/(hi-lo);
Linop.HermOp(T0,y);
T1=y*xscale+in*mscale;
// sum = .5 c[0] T0 + c[1] T1
out = (0.5*Coeffs[0])*T0 + Coeffs[1]*T1;
for(int n=2;n<order;n++){
Linop.HermOp(*Tn,y);
y=xscale*y+mscale*(*Tn);
*Tnp=2.0*y-(*Tnm);
out=out+Coeffs[n]* (*Tnp);
// Cycle pointers to avoid copies
Field *swizzle = Tnm;
Tnm =Tn;
Tn =Tnp;
Tnp =swizzle;
}
}
};
template<class Field>
class ChebyshevLanczos : public Chebyshev<Field> {
private:
std::vector<RealD> Coeffs;
int order;
RealD alpha;
RealD beta;
RealD mu;
public:
ChebyshevLanczos(RealD _alpha,RealD _beta,RealD _mu,int _order) :
alpha(_alpha), alpha(_alpha),
beta(_beta), beta(_beta),
mu(_mu) mu(_mu)
{ {
order=_order; order=_order;
Coeffs.resize(order); Coeffs.resize(order);
for(int i=0;i<_order;i++){ for(int i=0;i<_order;i++){
Coeffs[i] = 0.0; Coeffs[i] = 0.0;
}
Coeffs[order-1]=1.0;
};
void csv(std::ostream &out){
for (RealD x=-1.2*alpha; x<1.2*alpha; x+=(2.0*alpha)/10000) {
RealD f = approx(x);
out<< x<<" "<<f<<std::endl;
}
return;
}
RealD approx(RealD xx) // Convenience for plotting the approximation
{
RealD Tn;
RealD Tnm;
RealD Tnp;
Real aa = alpha * alpha;
Real bb = beta * beta;
RealD x = ( 2.0 * (xx-mu)*(xx-mu) - (aa+bb) ) / (aa-bb);
RealD y= x;
RealD T0=1;
RealD T1=y;
RealD sum;
sum = 0.5*Coeffs[0]*T0;
sum+= Coeffs[1]*T1;
Tn =T1;
Tnm=T0;
for(int i=2;i<order;i++){
Tnp=2*y*Tn-Tnm;
Tnm=Tn;
Tn =Tnp;
sum+= Tn*Coeffs[i];
}
return sum;
};
// shift_Multiply in Rudy's code
void AminusMuSq(LinearOperatorBase<Field> &Linop, const Field &in, Field &out)
{
GridBase *grid=in._grid;
Field tmp(grid);
RealD aa= alpha*alpha;
RealD bb= beta * beta;
Linop.HermOp(in,out);
out = out - mu*in;
Linop.HermOp(out,tmp);
tmp = tmp - mu * out;
out = (2.0/ (aa-bb) ) * tmp - ((aa+bb)/(aa-bb))*in;
};
// Implement the required interface
void operator() (LinearOperatorBase<Field> &Linop, const Field &in, Field &out) {
GridBase *grid=in._grid;
int vol=grid->gSites();
Field T0(grid); T0 = in;
Field T1(grid);
Field T2(grid);
Field y(grid);
Field *Tnm = &T0;
Field *Tn = &T1;
Field *Tnp = &T2;
// Tn=T1 = (xscale M )*in
AminusMuSq(Linop,T0,T1);
// sum = .5 c[0] T0 + c[1] T1
out = (0.5*Coeffs[0])*T0 + Coeffs[1]*T1;
for(int n=2;n<order;n++){
AminusMuSq(Linop,*Tn,y);
*Tnp=2.0*y-(*Tnm);
out=out+Coeffs[n]* (*Tnp);
// Cycle pointers to avoid copies
Field *swizzle = Tnm;
Tnm =Tn;
Tn =Tnp;
Tnp =swizzle;
}
} }
Coeffs[order-1]=1.0;
}; };
}
void csv(std::ostream &out){
for (RealD x=-1.2*alpha; x<1.2*alpha; x+=(2.0*alpha)/10000) {
RealD f = approx(x);
out<< x<<" "<<f<<std::endl;
}
return;
}
RealD approx(RealD xx) // Convenience for plotting the approximation
{
RealD Tn;
RealD Tnm;
RealD Tnp;
Real aa = alpha * alpha;
Real bb = beta * beta;
RealD x = ( 2.0 * (xx-mu)*(xx-mu) - (aa+bb) ) / (aa-bb);
RealD y= x;
RealD T0=1;
RealD T1=y;
RealD sum;
sum = 0.5*Coeffs[0]*T0;
sum+= Coeffs[1]*T1;
Tn =T1;
Tnm=T0;
for(int i=2;i<order;i++){
Tnp=2*y*Tn-Tnm;
Tnm=Tn;
Tn =Tnp;
sum+= Tn*Coeffs[i];
}
return sum;
};
// shift_Multiply in Rudy's code
void AminusMuSq(LinearOperatorBase<Field> &Linop, const Field &in, Field &out)
{
GridBase *grid=in._grid;
Field tmp(grid);
RealD aa= alpha*alpha;
RealD bb= beta * beta;
Linop.HermOp(in,out);
out = out - mu*in;
Linop.HermOp(out,tmp);
tmp = tmp - mu * out;
out = (2.0/ (aa-bb) ) * tmp - ((aa+bb)/(aa-bb))*in;
};
// Implement the required interface
void operator() (LinearOperatorBase<Field> &Linop, const Field &in, Field &out) {
GridBase *grid=in._grid;
int vol=grid->gSites();
Field T0(grid); T0 = in;
Field T1(grid);
Field T2(grid);
Field y(grid);
Field *Tnm = &T0;
Field *Tn = &T1;
Field *Tnp = &T2;
// Tn=T1 = (xscale M )*in
AminusMuSq(Linop,T0,T1);
// sum = .5 c[0] T0 + c[1] T1
out = (0.5*Coeffs[0])*T0 + Coeffs[1]*T1;
for(int n=2;n<order;n++){
AminusMuSq(Linop,*Tn,y);
*Tnp=2.0*y-(*Tnm);
out=out+Coeffs[n]* (*Tnp);
// Cycle pointers to avoid copies
Field *swizzle = Tnm;
Tnm =Tn;
Tn =Tnp;
Tnp =swizzle;
}
}
};
NAMESPACE_END(Grid);
#endif #endif

228
lib/algorithms/approx/Forecast.h
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@ -26,127 +26,127 @@ with this program; if not, write to the Free Software Foundation, Inc.,
See the full license in the file "LICENSE" in the top level distribution directory See the full license in the file "LICENSE" in the top level distribution directory
*************************************************************************************/ *************************************************************************************/
/* END LEGAL */ /* END LEGAL */
#ifndef INCLUDED_FORECAST_H #ifndef INCLUDED_FORECAST_H
#define INCLUDED_FORECAST_H #define INCLUDED_FORECAST_H
namespace Grid { NAMESPACE_BEGIN(Grid);
// Abstract base class. // Abstract base class.
// Takes a matrix (Mat), a source (phi), and a vector of Fields (chi) // Takes a matrix (Mat), a source (phi), and a vector of Fields (chi)
// and returns a forecasted solution to the system D*psi = phi (psi). // and returns a forecasted solution to the system D*psi = phi (psi).
template<class Matrix, class Field> template<class Matrix, class Field>
class Forecast class Forecast
{
public:
virtual Field operator()(Matrix &Mat, const Field& phi, const std::vector<Field>& chi) = 0;
};
// Implementation of Brower et al.'s chronological inverter (arXiv:hep-lat/9509012),
// used to forecast solutions across poles of the EOFA heatbath.
//
// Modified from CPS (cps_pp/src/util/dirac_op/d_op_base/comsrc/minresext.C)
template<class Matrix, class Field>
class ChronoForecast : public Forecast<Matrix,Field>
{
public:
Field operator()(Matrix &Mat, const Field& phi, const std::vector<Field>& prev_solns)
{ {
public: int degree = prev_solns.size();
virtual Field operator()(Matrix &Mat, const Field& phi, const std::vector<Field>& chi) = 0; Field chi(phi); // forecasted solution
// Trivial cases
if(degree == 0){ chi = zero; return chi; }
else if(degree == 1){ return prev_solns[0]; }
RealD dot;
ComplexD xp;
Field r(phi); // residual
Field Mv(phi);
std::vector<Field> v(prev_solns); // orthonormalized previous solutions
std::vector<Field> MdagMv(degree,phi);
// Array to hold the matrix elements
std::vector<std::vector<ComplexD>> G(degree, std::vector<ComplexD>(degree));
// Solution and source vectors
std::vector<ComplexD> a(degree);
std::vector<ComplexD> b(degree);
// Orthonormalize the vector basis
for(int i=0; i<degree; i++){
v[i] *= 1.0/std::sqrt(norm2(v[i]));
for(int j=i+1; j<degree; j++){ v[j] -= innerProduct(v[i],v[j]) * v[i]; }
}
// Perform sparse matrix multiplication and construct rhs
for(int i=0; i<degree; i++){
b[i] = innerProduct(v[i],phi);
Mat.M(v[i],Mv);
Mat.Mdag(Mv,MdagMv[i]);
G[i][i] = innerProduct(v[i],MdagMv[i]);
}
// Construct the matrix
for(int j=0; j<degree; j++){
for(int k=j+1; k<degree; k++){
G[j][k] = innerProduct(v[j],MdagMv[k]);
G[k][j] = std::conj(G[j][k]);
}}
// Gauss-Jordan elimination with partial pivoting
for(int i=0; i<degree; i++){
// Perform partial pivoting
int k = i;
for(int j=i+1; j<degree; j++){ if(std::abs(G[j][j]) > std::abs(G[k][k])){ k = j; } }
if(k != i){
xp = b[k];
b[k] = b[i];
b[i] = xp;
for(int j=0; j<degree; j++){
xp = G[k][j];
G[k][j] = G[i][j];
G[i][j] = xp;
}
}
// Convert matrix to upper triangular form
for(int j=i+1; j<degree; j++){
xp = G[j][i]/G[i][i];
b[j] -= xp * b[i];
for(int k=0; k<degree; k++){ G[j][k] -= xp*G[i][k]; }
}
}
// Use Gaussian elimination to solve equations and calculate initial guess
chi = zero;
r = phi;
for(int i=degree-1; i>=0; i--){
a[i] = 0.0;
for(int j=i+1; j<degree; j++){ a[i] += G[i][j] * a[j]; }
a[i] = (b[i]-a[i])/G[i][i];
chi += a[i]*v[i];
r -= a[i]*MdagMv[i];
}
RealD true_r(0.0);
ComplexD tmp;
for(int i=0; i<degree; i++){
tmp = -b[i];
for(int j=0; j<degree; j++){ tmp += G[i][j]*a[j]; }
tmp = std::conj(tmp)*tmp;
true_r += std::sqrt(tmp.real());
}
RealD error = std::sqrt(norm2(r)/norm2(phi));
std::cout << GridLogMessage << "ChronoForecast: |res|/|src| = " << error << std::endl;
return chi;
}; };
};
// Implementation of Brower et al.'s chronological inverter (arXiv:hep-lat/9509012), NAMESPACE_END(Grid);
// used to forecast solutions across poles of the EOFA heatbath.
//
// Modified from CPS (cps_pp/src/util/dirac_op/d_op_base/comsrc/minresext.C)
template<class Matrix, class Field>
class ChronoForecast : public Forecast<Matrix,Field>
{
public:
Field operator()(Matrix &Mat, const Field& phi, const std::vector<Field>& prev_solns)
{
int degree = prev_solns.size();
Field chi(phi); // forecasted solution
// Trivial cases
if(degree == 0){ chi = zero; return chi; }
else if(degree == 1){ return prev_solns[0]; }
RealD dot;
ComplexD xp;
Field r(phi); // residual
Field Mv(phi);
std::vector<Field> v(prev_solns); // orthonormalized previous solutions
std::vector<Field> MdagMv(degree,phi);
// Array to hold the matrix elements
std::vector<std::vector<ComplexD>> G(degree, std::vector<ComplexD>(degree));
// Solution and source vectors
std::vector<ComplexD> a(degree);
std::vector<ComplexD> b(degree);
// Orthonormalize the vector basis
for(int i=0; i<degree; i++){
v[i] *= 1.0/std::sqrt(norm2(v[i]));
for(int j=i+1; j<degree; j++){ v[j] -= innerProduct(v[i],v[j]) * v[i]; }
}
// Perform sparse matrix multiplication and construct rhs
for(int i=0; i<degree; i++){
b[i] = innerProduct(v[i],phi);
Mat.M(v[i],Mv);
Mat.Mdag(Mv,MdagMv[i]);
G[i][i] = innerProduct(v[i],MdagMv[i]);
}
// Construct the matrix
for(int j=0; j<degree; j++){
for(int k=j+1; k<degree; k++){
G[j][k] = innerProduct(v[j],MdagMv[k]);
G[k][j] = std::conj(G[j][k]);
}}
// Gauss-Jordan elimination with partial pivoting
for(int i=0; i<degree; i++){
// Perform partial pivoting
int k = i;
for(int j=i+1; j<degree; j++){ if(std::abs(G[j][j]) > std::abs(G[k][k])){ k = j; } }
if(k != i){
xp = b[k];
b[k] = b[i];
b[i] = xp;
for(int j=0; j<degree; j++){
xp = G[k][j];
G[k][j] = G[i][j];
G[i][j] = xp;
}
}
// Convert matrix to upper triangular form
for(int j=i+1; j<degree; j++){
xp = G[j][i]/G[i][i];
b[j] -= xp * b[i];
for(int k=0; k<degree; k++){ G[j][k] -= xp*G[i][k]; }
}
}
// Use Gaussian elimination to solve equations and calculate initial guess
chi = zero;
r = phi;
for(int i=degree-1; i>=0; i--){
a[i] = 0.0;
for(int j=i+1; j<degree; j++){ a[i] += G[i][j] * a[j]; }
a[i] = (b[i]-a[i])/G[i][i];
chi += a[i]*v[i];
r -= a[i]*MdagMv[i];
}
RealD true_r(0.0);
ComplexD tmp;
for(int i=0; i<degree; i++){
tmp = -b[i];
for(int j=0; j<degree; j++){ tmp += G[i][j]*a[j]; }
tmp = std::conj(tmp)*tmp;
true_r += std::sqrt(tmp.real());
}
RealD error = std::sqrt(norm2(r)/norm2(phi));
std::cout << GridLogMessage << "ChronoForecast: |res|/|src| = " << error << std::endl;
return chi;
};
};
}
#endif #endif

5
lib/algorithms/approx/MultiShiftFunction.cc
View File

@ -27,7 +27,8 @@ Author: Azusa Yamaguchi <ayamaguc@staffmail.ed.ac.uk>
/* END LEGAL */ /* END LEGAL */
#include <Grid/GridCore.h> #include <Grid/GridCore.h>
namespace Grid { NAMESPACE_BEGIN(Grid);
double MultiShiftFunction::approx(double x) double MultiShiftFunction::approx(double x)
{ {
double a = norm; double a = norm;
@ -53,4 +54,4 @@ void MultiShiftFunction::csv(std::ostream &out)
} }
return; return;
} }
} NAMESPACE_END(Grid);

4
lib/algorithms/approx/MultiShiftFunction.h
View File

@ -29,7 +29,7 @@ Author: Peter Boyle <paboyle@ph.ed.ac.uk>
#ifndef MULTI_SHIFT_FUNCTION #ifndef MULTI_SHIFT_FUNCTION
#define MULTI_SHIFT_FUNCTION #define MULTI_SHIFT_FUNCTION
namespace Grid { NAMESPACE_BEGIN(Grid);
class MultiShiftFunction { class MultiShiftFunction {
public: public:
@ -63,5 +63,5 @@ public:
} }
}; };
} NAMESPACE_END(Grid);
#endif #endif

7
lib/algorithms/approx/Zolotarev.cc
View File

@ -58,8 +58,8 @@
/* Compute the partial fraction expansion coefficients (alpha) from the /* Compute the partial fraction expansion coefficients (alpha) from the
* factored form */ * factored form */
namespace Grid { NAMESPACE_BEGIN(Grid);
namespace Approx { NAMESPACE_BEGIN(Approx);
static void construct_partfrac(izd *z) { static void construct_partfrac(izd *z) {
int dn = z -> dn, dd = z -> dd, type = z -> type; int dn = z -> dn, dd = z -> dd, type = z -> type;
@ -723,5 +723,6 @@ int main(int argc, char** argv) {
return EXIT_SUCCESS; return EXIT_SUCCESS;
} }
#endif /* TEST */ #endif /* TEST */
NAMESPACE_END(Approx);
NAMESPACE_END(Grid);

9
lib/algorithms/approx/Zolotarev.h
View File

@ -1,13 +1,13 @@
/* -*- Mode: C; comment-column: 22; fill-column: 79; -*- */ /* -*- Mode: C; comment-column: 22; fill-column: 79; -*- */
#ifdef __cplusplus #ifdef __cplusplus
namespace Grid { #include <Grid/Namespace.h>
namespace Approx { NAMESPACE_BEGIN(Grid);
NAMESPACE_BEGIN(Approx);
#endif #endif
#define HVERSION Header Time-stamp: <14-OCT-2004 09:26:51.00 adk@MISSCONTRARY> #define HVERSION Header Time-stamp: <14-OCT-2004 09:26:51.00 adk@MISSCONTRARY>
#ifndef ZOLOTAREV_INTERNAL #ifndef ZOLOTAREV_INTERNAL
#ifndef PRECISION #ifndef PRECISION
#define PRECISION double #define PRECISION double
@ -83,5 +83,6 @@ void zolotarev_free(zolotarev_data *zdata);
#endif #endif
#ifdef __cplusplus #ifdef __cplusplus
}} NAMESPACE_END(Approx);
NAMESPACE_END(Grid);
#endif #endif