mirror of
https://github.com/paboyle/Grid.git
synced 2024-11-10 15:55:37 +00:00
d1afebf71e
6000 matmuls CG unprec 2000 matmuls CG prec (4000 eo muls) 1050 matmuls PGCR on 16^3 x 32 x 8 m=.01 Substantial effort on timing and logging infrastructure
155 lines
3.5 KiB
C++
155 lines
3.5 KiB
C++
#ifndef GRID_CHEBYSHEV_H
|
|
#define GRID_CHEBYSHEV_H
|
|
|
|
#include<Grid.h>
|
|
#include<algorithms/LinearOperator.h>
|
|
|
|
namespace Grid {
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////
|
|
// Simple general polynomial with user supplied coefficients
|
|
////////////////////////////////////////////////////////////////////////////////////////////
|
|
template<class Field>
|
|
class Polynomial : public OperatorFunction<Field> {
|
|
private:
|
|
std::vector<double> Coeffs;
|
|
public:
|
|
Polynomial(std::vector<double> &_Coeffs) : Coeffs(_Coeffs) {};
|
|
|
|
// Implement the required interface
|
|
void operator() (LinearOperatorBase<Field> &Linop, const Field &in, Field &out) {
|
|
|
|
Field AtoN = in;
|
|
out = AtoN*Coeffs[0];
|
|
|
|
for(int n=1;n<Coeffs.size();n++){
|
|
Field Mtmp=AtoN;
|
|
Linop.Op(Mtmp,AtoN);
|
|
out=out+AtoN*Coeffs[n];
|
|
}
|
|
};
|
|
};
|
|
|
|
////////////////////////////////////////////////////////////////////////////////////////////
|
|
// Generic Chebyshev approximations
|
|
////////////////////////////////////////////////////////////////////////////////////////////
|
|
template<class Field>
|
|
class Chebyshev : public OperatorFunction<Field> {
|
|
private:
|
|
std::vector<double> Coeffs;
|
|
int order;
|
|
double hi;
|
|
double lo;
|
|
|
|
public:
|
|
void csv(std::ostream &out){
|
|
for (double x=lo; x<hi; x+=(hi-lo)/1000) {
|
|
double f = approx(x);
|
|
out<< x<<" "<<f<<std::endl;
|
|
}
|
|
return;
|
|
}
|
|
|
|
// Convenience for plotting the approximation
|
|
void PlotApprox(std::ostream &out) {
|
|
out<<"Polynomial approx ["<<lo<<","<<hi<<"]"<<std::endl;
|
|
for(double x=lo;x<hi;x+=(hi-lo)/50.0){
|
|
out <<x<<"\t"<<approx(x)<<std::endl;
|
|
}
|
|
};
|
|
|
|
|
|
Chebyshev(double _lo,double _hi,int _order, double (* func)(double) ){
|
|
lo=_lo;
|
|
hi=_hi;
|
|
order=_order;
|
|
|
|
if(order < 2) exit(-1);
|
|
Coeffs.resize(order);
|
|
for(int j=0;j<order;j++){
|
|
double s=0;
|
|
for(int k=0;k<order;k++){
|
|
double y=std::cos(M_PI*(k+0.5)/order);
|
|
double x=0.5*(y*(hi-lo)+(hi+lo));
|
|
double f=func(x);
|
|
s=s+f*std::cos( j*M_PI*(k+0.5)/order );
|
|
}
|
|
Coeffs[j] = s * 2.0/order;
|
|
}
|
|
};
|
|
|
|
double approx(double x) // Convenience for plotting the approximation
|
|
{
|
|
double Tn;
|
|
double Tnm;
|
|
double Tnp;
|
|
|
|
double y=( x-0.5*(hi+lo))/(0.5*(hi-lo));
|
|
|
|
double T0=1;
|
|
double T1=y;
|
|
|
|
double 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;
|
|
};
|
|
|
|
// 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;
|
|
|
|
std::cout<<GridLogMessage << "Chebyshev ["<<lo<<","<<hi<<"]"<< " order "<<order <<std::endl;
|
|
// Tn=T1 = (xscale M + mscale)in
|
|
double xscale = 2.0/(hi-lo);
|
|
double 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;
|
|
|
|
}
|
|
}
|
|
};
|
|
|
|
|
|
}
|
|
#endif
|