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Grid/Grid/qcd/smearing/HISQSmearing.h
Peter Boyle 93d0a1e73a HISQ view call
2024-04-01 14:16:47 -04:00

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/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./lib/qcd/smearing/HISQSmearing.h
Copyright (C) 2023
Author: D. A. Clarke <clarke.davida@gmail.com>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
See the full license in the file "LICENSE" in the top level distribution
directory
*************************************************************************************/
/*
@file HISQSmearing.h
@brief Declares classes related to HISQ smearing
*/
#pragma once
#include <Grid/Grid.h>
#include <Grid/lattice/PaddedCell.h>
#include <Grid/stencil/GeneralLocalStencil.h>
NAMESPACE_BEGIN(Grid);
// TODO: find a way to fold this into the stencil header. need to access grid to get
// Nd, since you don't want to inherit from QCD.h
/*! @brief append arbitrary shift path to shifts */
template<typename... Args>
void appendShift(std::vector<Coordinate>& shifts, int dir, Args... args) {
Coordinate shift(Nd,0);
generalShift(shift, dir, args...);
// push_back creates an element at the end of shifts and
// assigns the data in the argument to it.
shifts.push_back(shift);
}
/*! @brief figure out the stencil index from mu and nu */
accelerator_inline int stencilIndex(int mu, int nu) {
// Nshifts depends on how you built the stencil
int Nshifts = 6;
return Nshifts*nu + Nd*Nshifts*mu;
}
/*! @brief structure holding the link treatment */
struct SmearingParameters{
SmearingParameters(){}
Real c_1; // 1 link
Real c_naik; // Naik term
Real c_3; // 3 link
Real c_5; // 5 link
Real c_7; // 7 link
Real c_lp; // 5 link Lepage
SmearingParameters(Real c1, Real cnaik, Real c3, Real c5, Real c7, Real clp)
: c_1(c1),
c_naik(cnaik),
c_3(c3),
c_5(c5),
c_7(c7),
c_lp(clp){}
};
/*! @brief create fat links from link variables */
template<class Gimpl>
class Smear_HISQ : public Gimpl {
private:
GridCartesian* const _grid;
SmearingParameters _linkTreatment;
public:
INHERIT_GIMPL_TYPES(Gimpl);
typedef typename Gimpl::GaugeField GF;
typedef typename Gimpl::GaugeLinkField LF;
typedef typename Gimpl::ComplexField CF;
// Don't allow default values here.
Smear_HISQ(GridCartesian* grid, Real c1, Real cnaik, Real c3, Real c5, Real c7, Real clp)
: _grid(grid),
_linkTreatment(c1,cnaik,c3,c5,c7,clp) {
assert(Nc == 3 && "HISQ smearing currently implemented only for Nc==3");
assert(Nd == 4 && "HISQ smearing only defined for Nd==4");
}
// Allow to pass a pointer to a C-style, double array for MILC convenience
Smear_HISQ(GridCartesian* grid, double* coeff)
: _grid(grid),
_linkTreatment(coeff[0],coeff[1],coeff[2],coeff[3],coeff[4],coeff[5]) {
assert(Nc == 3 && "HISQ smearing currently implemented only for Nc==3");
assert(Nd == 4 && "HISQ smearing only defined for Nd==4");
}
~Smear_HISQ() {}
// Intent: OUT--u_smr, u_naik
// IN--u_thin
void smear(GF& u_smr, GF& u_naik, GF& u_thin) const {
SmearingParameters lt = this->_linkTreatment;
auto grid = this->_grid;
// Create a padded cell of extra padding depth=1 and fill the padding.
int depth = 1;
PaddedCell Ghost(depth,grid);
GF Ughost = Ghost.Exchange(u_thin);
// This is where auxiliary N-link fields and the final smear will be stored.
GF Ughost_fat(Ughost.Grid());
GF Ughost_3link(Ughost.Grid());
GF Ughost_5linkA(Ughost.Grid());
GF Ughost_5linkB(Ughost.Grid());
// mu-nu plane stencil. We allow mu==nu to make indexing the stencil easier,
// but these entries will not be used.
std::vector<Coordinate> shifts;
for(int mu=0;mu<Nd;mu++)
for(int nu=0;nu<Nd;nu++) {
appendShift(shifts,mu);
appendShift(shifts,nu);
appendShift(shifts,shiftSignal::NO_SHIFT);
appendShift(shifts,mu,Back(nu));
appendShift(shifts,Back(nu));
appendShift(shifts,Back(mu));
}
// A GeneralLocalStencil has two indices: a site and stencil index
GeneralLocalStencil gStencil(Ughost.Grid(),shifts);
// This is where contributions from the smearing get added together
Ughost_fat=Zero();
// This loop handles 3-, 5-, and 7-link constructs, minus Lepage and Naik.
for(int mu=0;mu<Nd;mu++) {
// TODO: This approach is slightly memory inefficient. It uses 25% extra memory
Ughost_3link =Zero();
Ughost_5linkA=Zero();
Ughost_5linkB=Zero();
// Create the accessors
autoView(U_v , Ughost , AcceleratorRead);
autoView(U_fat_v , Ughost_fat , AcceleratorWrite);
autoView(U_3link_v , Ughost_3link , AcceleratorWrite);
autoView(U_5linkA_v, Ughost_5linkA, AcceleratorWrite);
autoView(U_5linkB_v, Ughost_5linkB, AcceleratorWrite);
// We infer some types that will be needed in the calculation.
typedef decltype(gStencil.GetEntry(0,0)) stencilElement;
typedef decltype(coalescedReadGeneralPermute(U_v[0](0),gStencil.GetEntry(0,0)->_permute,Nd)) U3matrix;
int Nsites = U_v.size();
auto gStencil_v = gStencil.View(AcceleratorRead);
accelerator_for(site,Nsites,Simd::Nsimd(),{ // ----------- 3-link constructs
stencilElement SE0, SE1, SE2, SE3, SE4, SE5;
U3matrix U0, U1, U2, U3, U4, U5, W;
for(int nu=0;nu<Nd;nu++) {
if(nu==mu) continue;
int s = stencilIndex(mu,nu);
// The stencil gives us support points in the mu-nu plane that we will use to
// grab the links we need.
SE0 = gStencil_v.GetEntry(s+0,site); int x_p_mu = SE0->_offset;
SE1 = gStencil_v.GetEntry(s+1,site); int x_p_nu = SE1->_offset;
SE2 = gStencil_v.GetEntry(s+2,site); int x = SE2->_offset;
SE3 = gStencil_v.GetEntry(s+3,site); int x_p_mu_m_nu = SE3->_offset;
SE4 = gStencil_v.GetEntry(s+4,site); int x_m_nu = SE4->_offset;
SE5 = gStencil_v.GetEntry(s+5,site); int x_m_mu = SE5->_offset;
// When you're deciding whether to take an adjoint, the question is: how is the
// stored link oriented compared to the one you want? If I imagine myself travelling
// with the to-be-updated link, I have two possible, alternative 3-link paths I can
// take, one starting by going to the left, the other starting by going to the right.
U0 = coalescedReadGeneralPermute(U_v[x_p_mu ](nu),SE0->_permute,Nd);
U1 = coalescedReadGeneralPermute(U_v[x_p_nu ](mu),SE1->_permute,Nd);
U2 = coalescedReadGeneralPermute(U_v[x ](nu),SE2->_permute,Nd);
U3 = coalescedReadGeneralPermute(U_v[x_p_mu_m_nu](nu),SE3->_permute,Nd);
U4 = coalescedReadGeneralPermute(U_v[x_m_nu ](mu),SE4->_permute,Nd);
U5 = coalescedReadGeneralPermute(U_v[x_m_nu ](nu),SE4->_permute,Nd);
// "left" "right"
W = U2*U1*adj(U0) + adj(U5)*U4*U3;
// Save 3-link construct for later and add to smeared field.
coalescedWrite(U_3link_v[x](nu), W);
// The index operator (x) returns the coalesced read on GPU. The view [] index returns
// a reference to the vector object. The [x](mu) returns a reference to the densely
// packed (contiguous in memory) mu-th element of the vector object. On CPU,
// coalescedRead/Write is the identity mapping assigning vector object to vector object.
// But on GPU it's non-trivial and maps scalar object to vector object and vice versa.
coalescedWrite(U_fat_v[x](mu), U_fat_v(x)(mu) + lt.c_3*W);
}
})
accelerator_for(site,Nsites,Simd::Nsimd(),{ // ----------- 5-link
stencilElement SE0, SE1, SE2, SE3, SE4, SE5;
U3matrix U0, U1, U2, U3, U4, U5, W;
int sigmaIndex = 0;
for(int nu=0;nu<Nd;nu++) {
if(nu==mu) continue;
int s = stencilIndex(mu,nu);
for(int rho=0;rho<Nd;rho++) {
if (rho == mu || rho == nu) continue;
SE0 = gStencil_v.GetEntry(s+0,site); int x_p_mu = SE0->_offset;
SE1 = gStencil_v.GetEntry(s+1,site); int x_p_nu = SE1->_offset;
SE2 = gStencil_v.GetEntry(s+2,site); int x = SE2->_offset;
SE3 = gStencil_v.GetEntry(s+3,site); int x_p_mu_m_nu = SE3->_offset;
SE4 = gStencil_v.GetEntry(s+4,site); int x_m_nu = SE4->_offset;
U0 = coalescedReadGeneralPermute( U_v[x_p_mu ](nu ),SE0->_permute,Nd);
U1 = coalescedReadGeneralPermute(U_3link_v[x_p_nu ](rho),SE1->_permute,Nd);
U2 = coalescedReadGeneralPermute( U_v[x ](nu ),SE2->_permute,Nd);
U3 = coalescedReadGeneralPermute( U_v[x_p_mu_m_nu](nu ),SE3->_permute,Nd);
U4 = coalescedReadGeneralPermute(U_3link_v[x_m_nu ](rho),SE4->_permute,Nd);
U5 = coalescedReadGeneralPermute( U_v[x_m_nu ](nu ),SE4->_permute,Nd);
W = U2*U1*adj(U0) + adj(U5)*U4*U3;
if(sigmaIndex<3) {
coalescedWrite(U_5linkA_v[x](rho), W);
} else {
coalescedWrite(U_5linkB_v[x](rho), W);
}
coalescedWrite(U_fat_v[x](mu), U_fat_v(x)(mu) + lt.c_5*W);
sigmaIndex++;
}
}
})
accelerator_for(site,Nsites,Simd::Nsimd(),{ // ----------- 7-link
stencilElement SE0, SE1, SE2, SE3, SE4, SE5;
U3matrix U0, U1, U2, U3, U4, U5, W;
int sigmaIndex = 0;
for(int nu=0;nu<Nd;nu++) {
if(nu==mu) continue;
int s = stencilIndex(mu,nu);
for(int rho=0;rho<Nd;rho++) {
if (rho == mu || rho == nu) continue;
SE0 = gStencil_v.GetEntry(s+0,site); int x_p_mu = SE0->_offset;
SE1 = gStencil_v.GetEntry(s+1,site); int x_p_nu = SE1->_offset;
SE2 = gStencil_v.GetEntry(s+2,site); int x = SE2->_offset;
SE3 = gStencil_v.GetEntry(s+3,site); int x_p_mu_m_nu = SE3->_offset;
SE4 = gStencil_v.GetEntry(s+4,site); int x_m_nu = SE4->_offset;
U0 = coalescedReadGeneralPermute(U_v[x_p_mu](nu),SE0->_permute,Nd);
if(sigmaIndex<3) {
U1 = coalescedReadGeneralPermute(U_5linkB_v[x_p_nu](rho),SE1->_permute,Nd);
} else {
U1 = coalescedReadGeneralPermute(U_5linkA_v[x_p_nu](rho),SE1->_permute,Nd);
}
U2 = coalescedReadGeneralPermute(U_v[x](nu),SE2->_permute,Nd);
U3 = coalescedReadGeneralPermute(U_v[x_p_mu_m_nu](nu),SE3->_permute,Nd);
if(sigmaIndex<3) {
U4 = coalescedReadGeneralPermute(U_5linkB_v[x_m_nu](rho),SE4->_permute,Nd);
} else {
U4 = coalescedReadGeneralPermute(U_5linkA_v[x_m_nu](rho),SE4->_permute,Nd);
}
U5 = coalescedReadGeneralPermute(U_v[x_m_nu](nu),SE4->_permute,Nd);
W = U2*U1*adj(U0) + adj(U5)*U4*U3;
coalescedWrite(U_fat_v[x](mu), U_fat_v(x)(mu) + lt.c_7*W);
sigmaIndex++;
}
}
})
} // end mu loop
// c1, c3, c5, c7 construct contributions
u_smr = Ghost.Extract(Ughost_fat) + lt.c_1*u_thin;
// Load up U and V std::vectors to access thin and smeared links.
std::vector<LF> U(Nd, grid);
std::vector<LF> V(Nd, grid);
std::vector<LF> Vnaik(Nd, grid);
for (int mu = 0; mu < Nd; mu++) {
U[mu] = PeekIndex<LorentzIndex>(u_thin, mu);
V[mu] = PeekIndex<LorentzIndex>(u_smr, mu);
}
for(int mu=0;mu<Nd;mu++) {
// Naik
Vnaik[mu] = lt.c_naik*Gimpl::CovShiftForward(U[mu],mu,
Gimpl::CovShiftForward(U[mu],mu,
Gimpl::CovShiftIdentityForward(U[mu],mu)));
// LePage
for (int nu_h=1;nu_h<Nd;nu_h++) {
int nu=(mu+nu_h)%Nd;
// nu, nu, mu, Back(nu), Back(nu)
V[mu] = V[mu] + lt.c_lp*Gimpl::CovShiftForward(U[nu],nu,
Gimpl::CovShiftForward(U[nu],nu,
Gimpl::CovShiftForward(U[mu],mu,
Gimpl::CovShiftBackward(U[nu],nu,
Gimpl::CovShiftIdentityBackward(U[nu],nu)))))
// Back(nu), Back(nu), mu, nu, nu
+ lt.c_lp*Gimpl::CovShiftBackward(U[nu],nu,
Gimpl::CovShiftBackward(U[nu],nu,
Gimpl::CovShiftForward(U[mu],mu,
Gimpl::CovShiftForward(U[nu],nu,
Gimpl::CovShiftIdentityForward(U[nu],nu)))));
}
}
// Put V back into u_smr.
for (int mu = 0; mu < Nd; mu++) {
PokeIndex<LorentzIndex>(u_smr , V[mu] , mu);
PokeIndex<LorentzIndex>(u_naik, Vnaik[mu], mu);
}
};
// Intent: OUT--u_proj
// IN--u_mu
void projectU3(GF& u_proj, GF& u_mu) const {
auto grid = this->_grid;
LF V(grid), Q(grid), sqrtQinv(grid), id_3(grid), diff(grid);
CF c0(grid), c1(grid), c2(grid), g0(grid), g1(grid), g2(grid), S(grid), R(grid), theta(grid),
u(grid), v(grid), w(grid), den(grid), f0(grid), f1(grid), f2(grid);
// Follow MILC 10.1103/PhysRevD.82.074501, eqs (B2-B3) and (C1-C8)
for (int mu = 0; mu < Nd; mu++) {
V = PeekIndex<LorentzIndex>(u_mu, mu);
Q = adj(V)*V;
c0 = real(trace(Q));
c1 = (1/2.)*real(trace(Q*Q));
c2 = (1/3.)*real(trace(Q*Q*Q));
S = (1/3.)*c1-(1/18.)*c0*c0;
if (norm2(S)<1e-28) {
g0 = (1/3.)*c0; g1 = g0; g2 = g1;
} else {
R = (1/2.)*c2-(1/3. )*c0*c1+(1/27.)*c0*c0*c0;
theta = acos(R*pow(S,-1.5));
g0 = (1/3.)*c0+2.*sqrt(S)*cos((1/3.)*theta-2*M_PI/3.);
g1 = (1/3.)*c0+2.*sqrt(S)*cos((1/3.)*theta );
g2 = (1/3.)*c0+2.*sqrt(S)*cos((1/3.)*theta+2*M_PI/3.);
}
// if (fabs(Q.determinant()/(g0*g1*g2)-1.0) > 1e-5) { SVD }
u = sqrt(g0) + sqrt(g1) + sqrt(g2);
v = sqrt(g0*g1) + sqrt(g0*g2) + sqrt(g1*g2);
w = sqrt(g0*g1*g2);
den = w*(u*v-w);
f0 = (-w*(u*u+v)+u*v*v)/den;
f1 = (-w-u*u*u+2.*u*v)/den;
f2 = u/den;
id_3 = 1.;
sqrtQinv = f0*id_3 + f1*Q + f2*Q*Q;
PokeIndex<LorentzIndex>(u_proj, V*sqrtQinv, mu);
}
};
// void derivative(const GaugeField& Gauge) const {
// };
};
NAMESPACE_END(Grid);
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