latticegpu.jl/src/YM/YMhmc.jl
2021-07-19 02:03:31 +02:00

125 lines
3.8 KiB
Julia

###
### "THE BEER-WARE LICENSE":
### Alberto Ramos wrote this file. As long as you retain this
### notice you can do whatever you want with this stuff. If we meet some
### day, and you think this stuff is worth it, you can buy me a beer in
### return. <alberto.ramos@cern.ch>
###
### file: YMhmc.jl
### created: Thu Jul 15 11:27:28 2021
###
function gauge_action(U, lp::SpaceParm, gp::GaugeParm, kp::KernelParm, ymws::YMworkspace)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_plaq!(ymws.cm, U, lp)
end
S = gp.beta*( prod(lp.iL)*lp.npls -
CUDA.mapreduce(real, +, real.(ymws.cm))/gp.ng )
return S
end
function plaquette(U, lp::SpaceParm, gp::GaugeParm, kp::KernelParm, ymws::YMworkspace)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_plaq!(ymws.cm, U, lp)
end
return CUDA.mapreduce(real, +, real.(ymws.cm))/(prod(lp.iL)*lp.npls)
end
hamiltonian(mom, U, lp, gp, kp, ymws) = norm2(mom)/2.0 +
gauge_action(U, lp, gp, kp, ymws)
function HMC!(U, eps, ns, lp::SpaceParm, gp::GaugeParm, kp::KernelParm, ymws::YMworkspace; noacc=false)
ymws.U1 .= U
randomn!(ymws.mom)
hini = hamiltonian(ymws.mom, U, lp, gp, kp, ymws)
OMF4!(ymws.mom, U, eps, ns, lp, gp, kp, ymws)
dh = hamiltonian(ymws.mom, U, lp, gp, kp, ymws) - hini
pacc = exp(-dh)
acc = true
if (noacc)
return dh, acc
end
if (pacc < 1.0)
r = rand()
if (pacc < r)
U .= ymws.U1
acc = false
end
end
return dh, acc
end
function krnl_updt!(mom, frc1, frc2, eps1, U, eps2, lp::SpaceParm)
X = map2latt((CUDA.threadIdx().x,CUDA.threadIdx().y,CUDA.threadIdx().z),
(CUDA.blockIdx().x,CUDA.blockIdx().y,CUDA.blockIdx().z))
for id in 1:lp.ndim
mom[X,id] = mom[X,id] + eps1 * (frc1[X,id]+frc2[X,id])
U[X,id] = expm(U[X,id], mom[X,id], eps2)
end
return nothing
end
function OMF4!(mom, U, eps, ns, lp::SpaceParm, gp::GaugeParm, kp::KernelParm, ymws::YMworkspace)
r1::Float64 = 0.08398315262876693
r2::Float64 = 0.2539785108410595
r3::Float64 = 0.6822365335719091
r4::Float64 = -0.03230286765269967
r5::Float64 = 0.5-r1-r3
r6::Float64 = 1.0-2.0*(r2+r4)
ee = eps*gp.beta/gp.ng
force0_wilson!(ymws.frc1,ymws.frc2, U, lp, gp, kp)
for i in 1:ns
# STEP 1
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_updt!(ymws.mom, ymws.frc1,ymws.frc2, r1*ee, U, eps*r2, lp)
end
# STEP 2
force0_wilson!(ymws.frc1,ymws.frc2, U, lp, gp, kp)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_updt!(ymws.mom, ymws.frc1,ymws.frc2, r3*ee, U, eps*r4, lp)
end
# STEP 3
force0_wilson!(ymws.frc1,ymws.frc2, U, lp, gp, kp)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_updt!(ymws.mom, ymws.frc1,ymws.frc2, r5*ee, U, eps*r6, lp)
end
# STEP 4
force0_wilson!(ymws.frc1,ymws.frc2, U, lp, gp, kp)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_updt!(ymws.mom, ymws.frc1,ymws.frc2, r5*ee, U, eps*r4, lp)
end
# STEP 5
force0_wilson!(ymws.frc1,ymws.frc2, U, lp, gp, kp)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_updt!(ymws.mom, ymws.frc1,ymws.frc2, r3*ee, U, eps*r2, lp)
end
# STEP 6
force0_wilson!(ymws.frc1,ymws.frc2, U, lp, gp, kp)
CUDA.@sync begin
CUDA.@cuda threads=kp.threads blocks=kp.blocks krnl_updt!(ymws.mom, ymws.frc1,ymws.frc2, r1*ee, U, 0.0, lp)
end
end
return nothing
end