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mirror of https://github.com/paboyle/Grid.git synced 2024-09-20 09:15:38 +01:00

multishift conjugate gradient added and a strong test: take a diagonal

but non-identity matrix
l1 0  0  0 ....
0  l2 0  0 ....
0  0  l3 0 ...
.  .   .
.  .   .
.  .   .

And apply the multishift CG to it. Sum the poles and residues.
Insist that this be the same as the exactly taken square root
where l1,l2,l3 >= 0.
This commit is contained in:
Azusa Yamaguchi 2015-06-08 11:52:44 +01:00
parent 351c2905f5
commit 8688ff8b3a
11 changed files with 453 additions and 54 deletions

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@ -4,13 +4,16 @@
#include <algorithms/SparseMatrix.h>
#include <algorithms/LinearOperator.h>
#include <algorithms/approx/Zolotarev.h>
#include <algorithms/approx/Chebyshev.h>
#include <algorithms/approx/Remez.h>
#include <algorithms/approx/MultiShiftFunction.h>
#include <algorithms/iterative/ConjugateGradient.h>
#include <algorithms/iterative/NormalEquations.h>
#include <algorithms/iterative/SchurRedBlack.h>
#include <algorithms/approx/Zolotarev.h>
#include <algorithms/approx/Chebyshev.h>
#include <algorithms/approx/Remez.h>
#include <algorithms/iterative/ConjugateGradientMultiShift.h>
// Eigen/lanczos
// EigCg

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@ -1,4 +1,4 @@
HFILES=./algorithms/approx/bigfloat.h ./algorithms/approx/bigfloat_double.h ./algorithms/approx/Chebyshev.h ./algorithms/approx/Remez.h ./algorithms/approx/Zolotarev.h ./algorithms/iterative/ConjugateGradient.h ./algorithms/iterative/NormalEquations.h ./algorithms/iterative/SchurRedBlack.h ./algorithms/LinearOperator.h ./algorithms/SparseMatrix.h ./Algorithms.h ./AlignedAllocator.h ./cartesian/Cartesian_base.h ./cartesian/Cartesian_full.h ./cartesian/Cartesian_red_black.h ./Cartesian.h ./communicator/Communicator_base.h ./Communicator.h ./Comparison.h ./cshift/Cshift_common.h ./cshift/Cshift_mpi.h ./cshift/Cshift_none.h ./Cshift.h ./Grid.h ./GridConfig.h ./lattice/Lattice_arith.h ./lattice/Lattice_base.h ./lattice/Lattice_comparison.h ./lattice/Lattice_conformable.h ./lattice/Lattice_coordinate.h ./lattice/Lattice_ET.h ./lattice/Lattice_local.h ./lattice/Lattice_overload.h ./lattice/Lattice_peekpoke.h ./lattice/Lattice_reality.h ./lattice/Lattice_reduction.h ./lattice/Lattice_rng.h ./lattice/Lattice_trace.h ./lattice/Lattice_transfer.h ./lattice/Lattice_transpose.h ./lattice/Lattice_where.h ./Lattice.h ./parallelIO/NerscIO.h ./qcd/action/Actions.h ./qcd/action/fermion/CayleyFermion5D.h ./qcd/action/fermion/ContinuedFractionFermion5D.h ./qcd/action/fermion/DomainWallFermion.h ./qcd/action/fermion/FermionOperator.h ./qcd/action/fermion/MobiusFermion.h ./qcd/action/fermion/MobiusZolotarevFermion.h ./qcd/action/fermion/OverlapWilsonCayleyTanhFermion.h ./qcd/action/fermion/OverlapWilsonCayleyZolotarevFermion.h ./qcd/action/fermion/OverlapWilsonContfracTanhFermion.h ./qcd/action/fermion/OverlapWilsonContfracZolotarevFermion.h ./qcd/action/fermion/OverlapWilsonPartialFractionTanhFermion.h ./qcd/action/fermion/OverlapWilsonPartialFractionZolotarevFermion.h ./qcd/action/fermion/PartialFractionFermion5D.h ./qcd/action/fermion/ScaledShamirFermion.h ./qcd/action/fermion/ShamirZolotarevFermion.h ./qcd/action/fermion/WilsonCompressor.h ./qcd/action/fermion/WilsonFermion.h ./qcd/action/fermion/WilsonFermion5D.h ./qcd/action/fermion/WilsonKernels.h ./qcd/action/gauge/GaugeActionBase.h ./qcd/action/gauge/WilsonGaugeAction.h ./qcd/Dirac.h ./qcd/LinalgUtils.h ./qcd/QCD.h ./qcd/SpaceTimeGrid.h ./qcd/TwoSpinor.h ./qcd/utils/CovariantCshift.h ./qcd/utils/WilsonLoops.h ./simd/Grid_avx.h ./simd/Grid_avx512.h ./simd/Grid_qpx.h ./simd/Grid_sse4.h ./simd/Grid_vector_types.h ./simd/Old/Grid_vComplexD.h ./simd/Old/Grid_vComplexF.h ./simd/Old/Grid_vInteger.h ./simd/Old/Grid_vRealD.h ./simd/Old/Grid_vRealF.h ./Simd.h ./stencil/Lebesgue.h ./Stencil.h ./tensors/Tensor_arith.h ./tensors/Tensor_arith_add.h ./tensors/Tensor_arith_mac.h ./tensors/Tensor_arith_mul.h ./tensors/Tensor_arith_scalar.h ./tensors/Tensor_arith_sub.h ./tensors/Tensor_class.h ./tensors/Tensor_extract_merge.h ./tensors/Tensor_inner.h ./tensors/Tensor_outer.h ./tensors/Tensor_peek.h ./tensors/Tensor_poke.h ./tensors/Tensor_reality.h ./tensors/Tensor_Ta.h ./tensors/Tensor_trace.h ./tensors/Tensor_traits.h ./tensors/Tensor_transpose.h ./Tensors.h ./Threads.h
HFILES=./algorithms/approx/bigfloat.h ./algorithms/approx/bigfloat_double.h ./algorithms/approx/Chebyshev.h ./algorithms/approx/MultiShiftFunction.h ./algorithms/approx/Remez.h ./algorithms/approx/Zolotarev.h ./algorithms/iterative/ConjugateGradient.h ./algorithms/iterative/ConjugateGradientMultiShift.h ./algorithms/iterative/NormalEquations.h ./algorithms/iterative/SchurRedBlack.h ./algorithms/LinearOperator.h ./algorithms/SparseMatrix.h ./Algorithms.h ./AlignedAllocator.h ./cartesian/Cartesian_base.h ./cartesian/Cartesian_full.h ./cartesian/Cartesian_red_black.h ./Cartesian.h ./communicator/Communicator_base.h ./Communicator.h ./Comparison.h ./cshift/Cshift_common.h ./cshift/Cshift_mpi.h ./cshift/Cshift_none.h ./Cshift.h ./Grid.h ./GridConfig.h ./lattice/Lattice_arith.h ./lattice/Lattice_base.h ./lattice/Lattice_comparison.h ./lattice/Lattice_conformable.h ./lattice/Lattice_coordinate.h ./lattice/Lattice_ET.h ./lattice/Lattice_local.h ./lattice/Lattice_overload.h ./lattice/Lattice_peekpoke.h ./lattice/Lattice_reality.h ./lattice/Lattice_reduction.h ./lattice/Lattice_rng.h ./lattice/Lattice_trace.h ./lattice/Lattice_transfer.h ./lattice/Lattice_transpose.h ./lattice/Lattice_where.h ./Lattice.h ./parallelIO/NerscIO.h ./qcd/action/Actions.h ./qcd/action/fermion/CayleyFermion5D.h ./qcd/action/fermion/ContinuedFractionFermion5D.h ./qcd/action/fermion/DomainWallFermion.h ./qcd/action/fermion/FermionOperator.h ./qcd/action/fermion/MobiusFermion.h ./qcd/action/fermion/MobiusZolotarevFermion.h ./qcd/action/fermion/OverlapWilsonCayleyTanhFermion.h ./qcd/action/fermion/OverlapWilsonCayleyZolotarevFermion.h ./qcd/action/fermion/OverlapWilsonContfracTanhFermion.h ./qcd/action/fermion/OverlapWilsonContfracZolotarevFermion.h ./qcd/action/fermion/OverlapWilsonPartialFractionTanhFermion.h ./qcd/action/fermion/OverlapWilsonPartialFractionZolotarevFermion.h ./qcd/action/fermion/PartialFractionFermion5D.h ./qcd/action/fermion/ScaledShamirFermion.h ./qcd/action/fermion/ShamirZolotarevFermion.h ./qcd/action/fermion/WilsonCompressor.h ./qcd/action/fermion/WilsonFermion.h ./qcd/action/fermion/WilsonFermion5D.h ./qcd/action/fermion/WilsonKernels.h ./qcd/action/gauge/GaugeActionBase.h ./qcd/action/gauge/WilsonGaugeAction.h ./qcd/Dirac.h ./qcd/LinalgUtils.h ./qcd/QCD.h ./qcd/SpaceTimeGrid.h ./qcd/TwoSpinor.h ./qcd/utils/CovariantCshift.h ./qcd/utils/WilsonLoops.h ./simd/Grid_avx.h ./simd/Grid_avx512.h ./simd/Grid_qpx.h ./simd/Grid_sse4.h ./simd/Grid_vector_types.h ./simd/Old/Grid_vComplexD.h ./simd/Old/Grid_vComplexF.h ./simd/Old/Grid_vInteger.h ./simd/Old/Grid_vRealD.h ./simd/Old/Grid_vRealF.h ./Simd.h ./stencil/Lebesgue.h ./Stencil.h ./tensors/Tensor_arith.h ./tensors/Tensor_arith_add.h ./tensors/Tensor_arith_mac.h ./tensors/Tensor_arith_mul.h ./tensors/Tensor_arith_scalar.h ./tensors/Tensor_arith_sub.h ./tensors/Tensor_class.h ./tensors/Tensor_extract_merge.h ./tensors/Tensor_inner.h ./tensors/Tensor_outer.h ./tensors/Tensor_peek.h ./tensors/Tensor_poke.h ./tensors/Tensor_reality.h ./tensors/Tensor_Ta.h ./tensors/Tensor_trace.h ./tensors/Tensor_traits.h ./tensors/Tensor_transpose.h ./Tensors.h ./Threads.h
CCFILES=./algorithms/approx/Remez.cc ./algorithms/approx/Zolotarev.cc ./GridInit.cc ./qcd/action/fermion/CayleyFermion5D.cc ./qcd/action/fermion/ContinuedFractionFermion5D.cc ./qcd/action/fermion/PartialFractionFermion5D.cc ./qcd/action/fermion/WilsonFermion.cc ./qcd/action/fermion/WilsonFermion5D.cc ./qcd/action/fermion/WilsonKernels.cc ./qcd/action/fermion/WilsonKernelsHand.cc ./qcd/Dirac.cc ./qcd/SpaceTimeGrid.cc ./stencil/Lebesgue.cc ./stencil/Stencil_common.cc
CCFILES=./algorithms/approx/MultiShiftFunction.cc ./algorithms/approx/Remez.cc ./algorithms/approx/Zolotarev.cc ./GridInit.cc ./qcd/action/fermion/CayleyFermion5D.cc ./qcd/action/fermion/ContinuedFractionFermion5D.cc ./qcd/action/fermion/PartialFractionFermion5D.cc ./qcd/action/fermion/WilsonFermion.cc ./qcd/action/fermion/WilsonFermion5D.cc ./qcd/action/fermion/WilsonKernels.cc ./qcd/action/fermion/WilsonKernelsHand.cc ./qcd/Dirac.cc ./qcd/SpaceTimeGrid.cc ./stencil/Lebesgue.cc ./stencil/Stencil_common.cc

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@ -167,6 +167,14 @@ namespace Grid {
virtual void operator() (LinearOperatorBase<Field> &Linop, const Field &in, Field &out) = 0;
};
/////////////////////////////////////////////////////////////
// Base classes for Multishift solvers for operators
/////////////////////////////////////////////////////////////
template<class Field> class OperatorMultiFunction {
public:
virtual void operator() (LinearOperatorBase<Field> &Linop, const Field &in, std::vector<Field> &out) = 0;
};
// FIXME : To think about
// Chroma functionality list defining LinearOperator

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@ -0,0 +1,29 @@
#include <Grid.h>
namespace Grid {
double MultiShiftFunction::approx(double x)
{
double a = norm;
for(int n=0;n<poles.size();n++){
a = a + residues[n]/(x+poles[n]);
}
return a;
}
void MultiShiftFunction::gnuplot(std::ostream &out)
{
out<<"f(x) = "<<norm<<"";
for(int n=0;n<poles.size();n++){
out<<"+("<<residues[n]<<"/(x+"<<poles[n]<<"))";
}
out<<";"<<std::endl;
}
void MultiShiftFunction::csv(std::ostream &out)
{
for (double x=lo; x<hi; x*=1.05) {
double f = approx(x);
double r = sqrt(x);
out<< x<<","<<r<<","<<f<<","<<r-f<<std::endl;
}
return;
}
}

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@ -0,0 +1,28 @@
#ifndef MULTI_SHIFT_FUNCTION
#define MULTI_SHIFT_FUNCTION
namespace Grid {
class MultiShiftFunction {
public:
int order;
std::vector<RealD> poles;
std::vector<RealD> residues;
std::vector<RealD> tolerances;
RealD norm;
RealD lo,hi;
MultiShiftFunction(int n,RealD _lo,RealD _hi): poles(n), residues(n), lo(_lo), hi(_hi) {;};
RealD approx(RealD x);
void csv(std::ostream &out);
void gnuplot(std::ostream &out);
MultiShiftFunction(AlgRemez & remez,double tol,bool inverse) :
order(remez.getDegree()),
tolerances(remez.getDegree(),tol),
poles(remez.getDegree()),
residues(remez.getDegree())
{
remez.getBounds(lo,hi);
if ( inverse ) remez.getIPFE (&residues[0],&poles[0],&norm);
else remez.getPFE (&residues[0],&poles[0],&norm);
}
};
}
#endif

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@ -125,8 +125,17 @@ class AlgRemez
// Destructor
virtual ~AlgRemez();
int getDegree(void){
assert(n==d);
return n;
}
// Reset the bounds of the approximation
void setBounds(double lower, double upper);
// Reset the bounds of the approximation
void getBounds(double &lower, double &upper) {
lower=(double)apstrt;
upper=(double)apend;
}
// Generate the rational approximation x^(pnum/pden)
double generateApprox(int num_degree, int den_degree,

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@ -0,0 +1,250 @@
#ifndef GRID_CONJUGATE_MULTI_SHIFT_GRADIENT_H
#define GRID_CONJUGATE_MULTI_SHIFT_GRADIENT_H
namespace Grid {
/////////////////////////////////////////////////////////////
// Base classes for iterative processes based on operators
// single input vec, single output vec.
/////////////////////////////////////////////////////////////
template<class Field>
class ConjugateGradientMultiShift : public OperatorMultiFunction<Field>,
public OperatorFunction<Field>
{
public:
RealD Tolerance;
Integer MaxIterations;
int verbose;
MultiShiftFunction shifts;
ConjugateGradientMultiShift(Integer maxit,MultiShiftFunction &_shifts) :
MaxIterations(maxit),
shifts(_shifts)
{
verbose=1;
}
void operator() (LinearOperatorBase<Field> &Linop, const Field &src, Field &psi)
{
GridBase *grid = src._grid;
int nshift = shifts.order;
std::vector<Field> results(nshift,grid);
(*this)(Linop,src,results);
psi = shifts.norm*src;
for(int i=0;i<nshift;i++){
psi = psi + shifts.residues[i]*results[i];
}
return;
}
void operator() (LinearOperatorBase<Field> &Linop, const Field &src, std::vector<Field> &psi)
{
GridBase *grid = src._grid;
////////////////////////////////////////////////////////////////////////
// Convenience references to the info stored in "MultiShiftFunction"
////////////////////////////////////////////////////////////////////////
int nshift = shifts.order;
std::vector<RealD> &mass(shifts.poles); // Make references to array in "shifts"
std::vector<RealD> &mresidual(shifts.tolerances);
std::vector<RealD> alpha(nshift,1.0);
std::vector<Field> ps(nshift,grid);// Search directions
assert(psi.size()==nshift);
assert(mass.size()==nshift);
assert(mresidual.size()==nshift);
// dynamic sized arrays on stack; 2d is a pain with vector
RealD bs[nshift];
RealD rsq[nshift];
RealD z[nshift][2];
int converged[nshift];
const int primary =0;
//Primary shift fields CG iteration
RealD a,b,c,d;
RealD cp,bp,qq; //prev
// Matrix mult fields
Field r(grid);
Field p(grid);
Field tmp(grid);
Field mmp(grid);
// Check lightest mass
for(int s=0;s<nshift;s++){
assert( mass[s]>= mass[primary] );
converged[s]=0;
}
// Wire guess to zero
// Residuals "r" are src
// First search direction "p" is also src
cp = norm2(src);
for(int s=0;s<nshift;s++){
rsq[s] = cp * mresidual[s] * mresidual[s];
std::cout<<"ConjugateGradientMultiShift: shift "<<s
<<" target resid "<<rsq[s]<<std::endl;
ps[s] = src;
}
// r and p for primary
r=src;
p=src;
//MdagM+m[0]
Linop.HermOpAndNorm(p,mmp,d,qq);
axpy(mmp,mass[0],p,mmp);
RealD rn = norm2(p);
d += rn*mass[0];
// have verified that inner product of
// p and mmp is equal to d after this since
// the d computation is tricky
// qq = real(innerProduct(p,mmp));
// std::cout << "debug equal ? qq "<<qq<<" d "<< d<<std::endl;
b = -cp /d;
// Set up the various shift variables
int iz=0;
z[0][1-iz] = 1.0;
z[0][iz] = 1.0;
bs[0] = b;
for(int s=1;s<nshift;s++){
z[s][1-iz] = 1.0;
z[s][iz] = 1.0/( 1.0 - b*(mass[s]-mass[0]));
bs[s] = b*z[s][iz];
}
// r += b[0] A.p[0]
// c= norm(r)
c=axpy_norm(r,b,mmp,r);
for(int s=0;s<nshift;s++) {
axpby(psi[s],0.,-bs[s]*alpha[s],src,src);
}
// Iteration loop
int k;
for (k=1;k<=MaxIterations;k++){
a = c /cp;
axpy(p,a,p,r);
// Note to self - direction ps is iterated seperately
// for each shift. Does not appear to have any scope
// for avoiding linear algebra in "single" case.
//
// However SAME r is used. Could load "r" and update
// ALL ps[s]. 2/3 Bandwidth saving
// New Kernel: Load r, vector of coeffs, vector of pointers ps
for(int s=0;s<nshift;s++){
if ( ! converged[s] ) {
if (s==0){
axpy(ps[s],a,ps[s],r);
} else{
RealD as =a *z[s][iz]*bs[s] /(z[s][1-iz]*b);
axpby(ps[s],z[s][iz],as,r,ps[s]);
}
}
}
cp=c;
Linop.HermOpAndNorm(p,mmp,d,qq);
axpy(mmp,mass[0],p,mmp);
RealD rn = norm2(p);
d += rn*mass[0];
bp=b;
b=-cp/d;
c=axpy_norm(r,b,mmp,r);
// Toggle the recurrence history
bs[0] = b;
iz = 1-iz;
for(int s=1;s<nshift;s++){
if((!converged[s])){
RealD z0 = z[s][1-iz];
RealD z1 = z[s][iz];
z[s][iz] = z0*z1*bp
/ (b*a*(z1-z0) + z1*bp*(1- (mass[s]-mass[0])*b));
bs[s] = b*z[s][iz]/z0; // NB sign rel to Mike
}
}
for(int s=0;s<nshift;s++){
int ss = s;
// Scope for optimisation here in case of "single".
// Could load psi[0] and pull all ps[s] in.
// if ( single ) ss=primary;
// Bandwith saving in single case is Ls * 3 -> 2+Ls, so ~ 3x saving
// Pipelined CG gain:
//
// New Kernel: Load r, vector of coeffs, vector of pointers ps
// New Kernel: Load psi[0], vector of coeffs, vector of pointers ps
// If can predict the coefficient bs then we can fuse these and avoid write reread cyce
// on ps[s].
// Before: 3 x npole + 3 x npole
// After : 2 x npole (ps[s]) => 3x speed up of multishift CG.
if( (!converged[s]) ) {
axpy(psi[ss],-bs[s]*alpha[s],ps[s],psi[ss]);
}
}
// Convergence checks
int all_converged = 1;
for(int s=0;s<nshift;s++){
if ( (!converged[s]) ){
RealD css = c * z[s][iz]* z[s][iz];
if(css<rsq[s]){
if ( ! converged[s] )
std::cout<<"ConjugateGradientMultiShift k="<<k<<" Shift "<<s<<" has converged"<<std::endl;
converged[s]=1;
} else {
all_converged=0;
}
}
}
if ( all_converged ){
std::cout<< "CGMultiShift: All shifts have converged iteration "<<k<<std::endl;
std::cout<< "CGMultiShift: Checking solutions"<<std::endl;
// Check answers
for(int s=0; s < nshift; s++) {
Linop.HermOpAndNorm(psi[s],mmp,d,qq);
axpy(tmp,mass[s],psi[s],mmp);
axpy(r,-alpha[s],src,tmp);
RealD rn = norm2(r);
RealD cn = norm2(src);
std::cout<<"CGMultiShift: shift["<<s<<"] true residual "<<std::sqrt(rn/cn)<<std::endl;
}
return;
}
}
// ugly hack
std::cout<<"CG multi shift did not converge"<<std::endl;
assert(0);
}
};
}
#endif

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@ -1,5 +1,5 @@
bin_PROGRAMS = Test_GaugeAction Test_cayley_cg Test_cayley_even_odd Test_contfrac_cg Test_contfrac_even_odd Test_cshift Test_cshift_red_black Test_dwf_cg_prec Test_dwf_cg_schur Test_dwf_cg_unprec Test_dwf_even_odd Test_gamma Test_main Test_nersc_io Test_remez Test_rng Test_rng_fixed Test_simd Test_stencil Test_wilson_cg_prec Test_wilson_cg_schur Test_wilson_cg_unprec Test_wilson_even_odd
bin_PROGRAMS = Test_GaugeAction Test_cayley_cg Test_cayley_even_odd Test_contfrac_cg Test_contfrac_even_odd Test_cshift Test_cshift_red_black Test_dwf_cg_prec Test_dwf_cg_schur Test_dwf_cg_unprec Test_dwf_even_odd Test_gamma Test_main Test_multishift_sqrt Test_nersc_io Test_remez Test_rng Test_rng_fixed Test_simd Test_stencil Test_wilson_cg_prec Test_wilson_cg_schur Test_wilson_cg_unprec Test_wilson_even_odd
Test_GaugeAction_SOURCES=Test_GaugeAction.cc
@ -54,6 +54,10 @@ Test_main_SOURCES=Test_main.cc
Test_main_LDADD=-lGrid
Test_multishift_sqrt_SOURCES=Test_multishift_sqrt.cc
Test_multishift_sqrt_LDADD=-lGrid
Test_nersc_io_SOURCES=Test_nersc_io.cc
Test_nersc_io_LDADD=-lGrid

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@ -0,0 +1,110 @@
#include <Grid.h>
using namespace std;
using namespace Grid;
using namespace Grid::QCD;
template<class Field> class DumbOperator : public LinearOperatorBase<Field> {
public:
LatticeComplex scale;
LatticeComplex sqrtscale;
DumbOperator(GridBase *grid)
: scale(grid),
sqrtscale(grid)
{
GridParallelRNG pRNG(grid);
std::vector<int> seeds({5,6,7,8});
pRNG.SeedFixedIntegers(seeds);
random(pRNG,sqrtscale);
sqrtscale = sqrtscale * adj(sqrtscale);// force real pos def
scale = sqrtscale * sqrtscale;
}
void Op (const Field &in, Field &out){
out = scale * in;
}
void AdjOp (const Field &in, Field &out){
out = scale * in;
}
void HermOpAndNorm(const Field &in, Field &out,double &n1,double &n2){
ComplexD dot;
out = scale * in;
dot= innerProduct(in,out);
n1=real(dot);
dot = innerProduct(out,out);
n2=real(dot);
}
void ApplySqrt(const Field &in, Field &out){
out = sqrtscale * in;
}
};
int main (int argc, char ** argv)
{
Grid_init(&argc,&argv);
GridCartesian *grid = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(),
GridDefaultSimd(Nd,vComplexF::Nsimd()),
GridDefaultMpi());
double lo=0.001;
double hi=1.0;
int precision=64;
int degree=10;
AlgRemez remez(lo,hi,precision);
////////////////////////////////////////
// sqrt and inverse sqrt
////////////////////////////////////////
std::cout << "Generating degree "<<degree<<" for x^(1/2)"<<std::endl;
remez.generateApprox(degree,1,2);
MultiShiftFunction Sqrt(remez,1.0e-6,false);
GridParallelRNG pRNG(grid);
std::vector<int> seeds({1,2,3,4});
pRNG.SeedFixedIntegers(seeds);
LatticeFermion src(grid); random(pRNG,src);
LatticeFermion combined(grid);
LatticeFermion reference(grid);
LatticeFermion error(grid);
std::vector<LatticeFermion> result(degree,grid);
LatticeFermion summed(grid);
ConjugateGradientMultiShift<LatticeFermion> MSCG(10000,Sqrt);
DumbOperator<LatticeFermion> Diagonal(grid);
MSCG(Diagonal,src,result);
// double a = norm;
// for(int n=0;n<poles.size();n++){
// a = a + residues[n]/(x+poles[n]);
// }
assert(Sqrt.order==degree);
combined = Sqrt.norm*src;
for(int i=0;i<degree;i++){
combined = combined + Sqrt.residues[i]*result[i];
}
Diagonal.ApplySqrt(src,reference);
error = reference - combined;
std::cout << " Reference "<<norm2(reference)<<std::endl;
std::cout << " combined "<<norm2(combined) <<std::endl;
std::cout << " error "<<norm2(error) <<std::endl;
MSCG(Diagonal,src,summed);
error = summed - combined;
std::cout << " summed-combined "<<norm2(error) <<std::endl;
Grid_finalize();
}

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@ -4,43 +4,6 @@ using namespace std;
using namespace Grid;
using namespace Grid::QCD;
class MultiShiftFunction {
public:
std::vector<double> poles;
std::vector<double> residues;
double norm;
double lo,hi;
MultiShiftFunction(int n,double _lo,double _hi): poles(n), residues(n), lo(_lo), hi(_hi) {;};
double approx(double x);
void csv(std::ostream &out);
void gnuplot(std::ostream &out);
};
double MultiShiftFunction::approx(double x)
{
double a = norm;
for(int n=0;n<poles.size();n++){
a = a + residues[n]/(x+poles[n]);
}
return a;
}
void MultiShiftFunction::gnuplot(std::ostream &out)
{
out<<"f(x) = "<<norm<<"";
for(int n=0;n<poles.size();n++){
out<<"+("<<residues[n]<<"/(x+"<<poles[n]<<"))";
}
out<<";"<<std::endl;
}
void MultiShiftFunction::csv(std::ostream &out)
{
for (double x=lo; x<hi; x*=1.05) {
double f = approx(x);
double r = sqrt(x);
out<< x<<","<<r<<","<<f<<","<<r-f<<std::endl;
}
return;
}
int main (int argc, char ** argv)
{
Grid_init(&argc,&argv);
@ -56,22 +19,18 @@ int main (int argc, char ** argv)
////////////////////////////////////////
// sqrt and inverse sqrt
////////////////////////////////////////
MultiShiftFunction Sqrt(degree,lo,hi);
MultiShiftFunction InvSqrt(degree,lo,hi);
MultiShiftFunction SqrtSqrt(degree,lo,hi);
MultiShiftFunction InvSqrtSqrt(degree,lo,hi);
std::cout << "Generating degree "<<degree<<" for x^(1/2)"<<std::endl;
remez.generateApprox(degree,1,2);
remez.getPFE (& Sqrt.residues[0],& Sqrt.poles[0],& Sqrt.norm);
remez.getIPFE(&InvSqrt.residues[0],&InvSqrt.poles[0],&InvSqrt.norm);
MultiShiftFunction Sqrt(remez,1.0,false);
MultiShiftFunction InvSqrt(remez,1.0,true);
std::cout << "Generating degree "<<degree<<" for x^(1/4)"<<std::endl;
remez.generateApprox(degree,1,4);
remez.getPFE (&SqrtSqrt.residues[0],&SqrtSqrt.poles[0],&SqrtSqrt.norm);
remez.getIPFE(&InvSqrtSqrt.residues[0],&InvSqrtSqrt.poles[0],&InvSqrtSqrt.norm);
MultiShiftFunction SqrtSqrt(remez,1.0,false);
MultiShiftFunction InvSqrtSqrt(remez,1.0,true);
ofstream gnuplot(std::string("Sqrt.gnu"),std::ios::out|std::ios::trunc);
Sqrt.gnuplot(gnuplot);

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@ -20,7 +20,6 @@ int main (int argc, char ** argv)
{
Grid_init(&argc,&argv);
std::vector<int> latt_size = GridDefaultLatt();
std::vector<int> simd_layout = GridDefaultSimd(Nd,vComplexF::Nsimd());
std::vector<int> mpi_layout = GridDefaultMpi();