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DanielDoehringbennibolmranocha
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Simplify time integrators (#2481)
* start working on relaxation RK * start doc * docstrings + clean up * spell out * docstrings, remove secant * examples * tests * typo * increase allowed allocs * typo * test printing/show routines * rename to `u_tmp` * comment * reduce elixirs and tests * rename more explicitly * fmt * document * add sciml base * comments and format * more tests * docs * fix docs * refactor simple ssp * fix * test resize * remove unused resize! * Apply suggestions from code review * Apply suggestions from code review * Update src/time_integration/relaxation_methods/entropy_relaxation.jl * Apply suggestions from code review * Apply suggestions from code review * shorten * test * test vals * fix tet * R-RK: Newton and Sub-Diagonal * fmt * docs * Simplify Time Integrators * clean up docs * revisit * fix CI * Directly call `resize!` with `semi` and `volume_integral` * Update README.md Co-authored-by: Hendrik Ranocha <[email protected]> * Update docs/src/index.md Co-authored-by: Hendrik Ranocha <[email protected]> * remove sciml odeprob * Update src/time_integration/time_integration.jl Co-authored-by: Hendrik Ranocha <[email protected]> --------- Co-authored-by: bennibolm <[email protected]> Co-authored-by: Hendrik Ranocha <[email protected]>
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‎README.md‎

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@@ -46,6 +46,8 @@ installation and postprocessing procedures. Its features include:
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* [Explicit low-storage Runge-Kutta time integration](https://diffeq.sciml.ai/latest/solvers/ode_solve/#Low-Storage-Methods)
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* [Strong stability preserving methods](https://diffeq.sciml.ai/latest/solvers/ode_solve/#Explicit-Strong-Stability-Preserving-Runge-Kutta-Methods-for-Hyperbolic-PDEs-(Conservation-Laws))
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* CFL-based and error-based time step control
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* Custom explicit time integration schemes
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* Maximized linear stability via paired explicit Runge-Kutta methods
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* Native support for differentiable programming
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* Forward mode automatic differentiation via [ForwardDiff.jl](https://github.com/JuliaDiff/ForwardDiff.jl)
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* Periodic and weakly-enforced boundary conditions

‎docs/src/index.md‎

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@@ -42,6 +42,8 @@ installation and postprocessing procedures. Its features include:
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* [Explicit low-storage Runge-Kutta time integration](https://diffeq.sciml.ai/latest/solvers/ode_solve/#Low-Storage-Methods)
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* [Strong stability preserving methods](https://diffeq.sciml.ai/latest/solvers/ode_solve/#Explicit-Strong-Stability-Preserving-Runge-Kutta-Methods-for-Hyperbolic-PDEs-(Conservation-Laws))
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* CFL-based and error-based time step control
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* Custom explicit time integration schemes
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* Maximized linear stability via paired explicit Runge-Kutta methods
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* Native support for differentiable programming
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* Forward mode automatic differentiation via [ForwardDiff.jl](https://github.com/JuliaDiff/ForwardDiff.jl)
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* Periodic and weakly-enforced boundary conditions

‎docs/src/time_integration.md‎

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@@ -215,4 +215,4 @@ Then, the stable CFL number can be computed as described above.
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- [`Trixi.PairedExplicitRK2`](@ref): Second-order PERK method with at least two stages.
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- [`Trixi.PairedExplicitRK3`](@ref): Third-order PERK method with at least three stages.
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- [`Trixi.PairedExplicitRK4`](@ref): Fourth-order PERK method with at least five stages.
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- [`Trixi.PairedExplicitRK4`](@ref): Fourth-order PERK method with at least five stages.

‎src/solvers/dg.jl‎

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@@ -265,6 +265,18 @@ function Base.show(io::IO, mime::MIME"text/plain",
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end
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end
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# Required to be able to run `SimpleSSPRK33` without `VolumeIntegralSubcellLimiting`
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Base.resize!(semi, volume_integral::AbstractVolumeIntegral, new_size) = nothing
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function Base.resize!(semi, volume_integral::VolumeIntegralSubcellLimiting, new_size)
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# Resize container antidiffusive_fluxes
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resize!(semi.cache.antidiffusive_fluxes, new_size)
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# Resize container subcell_limiter_coefficients
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@unpack limiter = volume_integral
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resize!(limiter.cache.subcell_limiter_coefficients, new_size)
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end
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# TODO: FD. Should this definition live in a different file because it is
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# not strictly a DG method?
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"""

‎src/time_integration/methods_2N.jl‎

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@@ -6,7 +6,7 @@
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#! format: noindent
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# Abstract base type for time integration schemes of storage class `2N`
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abstract type SimpleAlgorithm2N end
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abstract type SimpleAlgorithm2N <: AbstractTimeIntegrationAlgorithm end
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"""
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CarpenterKennedy2N54()
@@ -75,25 +75,25 @@ struct CarpenterKennedy2N43 <: SimpleAlgorithm2N
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end
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# This struct is needed to fake https://github.com/SciML/OrdinaryDiffEq.jl/blob/0c2048a502101647ac35faabd80da8a5645beac7/src/integrators/type.jl#L1
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mutable struct SimpleIntegrator2NOptions{Callback}
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mutable struct SimpleIntegratorOptions{Callback}
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callback::Callback # callbacks; used in Trixi.jl
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adaptive::Bool # whether the algorithm is adaptive; ignored
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dtmax::Float64 # ignored
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maxiters::Int # maximal number of time steps
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tstops::Vector{Float64} # tstops from https://diffeq.sciml.ai/v6.8/basics/common_solver_opts/#Output-Control-1; ignored
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end
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function SimpleIntegrator2NOptions(callback, tspan; maxiters = typemax(Int), kwargs...)
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SimpleIntegrator2NOptions{typeof(callback)}(callback, false, Inf, maxiters,
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[last(tspan)])
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function SimpleIntegratorOptions(callback, tspan; maxiters = typemax(Int), kwargs...)
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SimpleIntegratorOptions{typeof(callback)}(callback, false, Inf, maxiters,
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[last(tspan)])
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end
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# This struct is needed to fake https://github.com/SciML/OrdinaryDiffEq.jl/blob/0c2048a502101647ac35faabd80da8a5645beac7/src/integrators/type.jl#L77
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# This implements the interface components described at
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# https://diffeq.sciml.ai/v6.8/basics/integrator/#Handing-Integrators-1
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# which are used in Trixi.jl.
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mutable struct SimpleIntegrator2N{RealT <: Real, uType, Params, Sol, F, Alg,
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SimpleIntegrator2NOptions} <: AbstractTimeIntegrator
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SimpleIntegratorOptions} <: AbstractTimeIntegrator
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u::uType
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du::uType
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u_tmp::uType
@@ -105,19 +105,10 @@ mutable struct SimpleIntegrator2N{RealT <: Real, uType, Params, Sol, F, Alg,
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sol::Sol # faked
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f::F # `rhs!` of the semidiscretization
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alg::Alg # SimpleAlgorithm2N
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opts::SimpleIntegrator2NOptions
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opts::SimpleIntegratorOptions
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finalstep::Bool # added for convenience
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end
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# Forward integrator.stats.naccept to integrator.iter (see GitHub PR#771)
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function Base.getproperty(integrator::SimpleIntegrator2N, field::Symbol)
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if field === :stats
115-
return (naccept = getfield(integrator, :iter),)
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end
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# general fallback
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return getfield(integrator, field)
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end
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function init(ode::ODEProblem, alg::SimpleAlgorithm2N;
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dt, callback::Union{CallbackSet, Nothing} = nothing, kwargs...)
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u = copy(ode.u0)
@@ -127,8 +118,8 @@ function init(ode::ODEProblem, alg::SimpleAlgorithm2N;
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iter = 0
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integrator = SimpleIntegrator2N(u, du, u_tmp, t, dt, zero(dt), iter, ode.p,
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(prob = ode,), ode.f, alg,
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SimpleIntegrator2NOptions(callback, ode.tspan;
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kwargs...), false)
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SimpleIntegratorOptions(callback, ode.tspan;
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kwargs...), false)
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# initialize callbacks
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if callback isa CallbackSet
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return integrator
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end
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# Fakes `solve`: https://diffeq.sciml.ai/v6.8/basics/overview/#Solving-the-Problems-1
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function solve(ode::ODEProblem, alg::SimpleAlgorithm2N;
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dt, callback = nothing, kwargs...)
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integrator = init(ode, alg, dt = dt, callback = callback; kwargs...)
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# Start actual solve
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solve!(integrator)
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end
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function solve!(integrator::SimpleIntegrator2N)
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@unpack prob = integrator.sol
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integrator.finalstep = false
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@trixi_timeit timer() "main loop" while !integrator.finalstep
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step!(integrator)
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end # "main loop" timer
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finalize_callbacks(integrator)
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return TimeIntegratorSolution((first(prob.tspan), integrator.t),
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(prob.u0, integrator.u),
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integrator.sol.prob)
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end
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function step!(integrator::SimpleIntegrator2N)
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@unpack prob = integrator.sol
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@unpack alg = integrator
@@ -225,22 +191,11 @@ function step!(integrator::SimpleIntegrator2N)
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end
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# get a cache where the RHS can be stored
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get_du(integrator::SimpleIntegrator2N) = integrator.du
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get_tmp_cache(integrator::SimpleIntegrator2N) = (integrator.u_tmp,)
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# some algorithms from DiffEq like FSAL-ones need to be informed when a callback has modified u
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u_modified!(integrator::SimpleIntegrator2N, ::Bool) = false
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# used by adaptive timestepping algorithms in DiffEq
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function set_proposed_dt!(integrator::SimpleIntegrator2N, dt)
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integrator.dt = dt
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end
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# Required e.g. for `glm_speed_callback`
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function get_proposed_dt(integrator::SimpleIntegrator2N)
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return integrator.dt
242-
end
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# stop the time integration
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function terminate!(integrator::SimpleIntegrator2N)
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integrator.finalstep = true

‎src/time_integration/methods_3Sstar.jl‎

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#! format: noindent
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# Abstract base type for time integration schemes of storage class `3S*`
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abstract type SimpleAlgorithm3Sstar end
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abstract type SimpleAlgorithm3Sstar <: AbstractTimeIntegrationAlgorithm end
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"""
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HypDiffN3Erk3Sstar52()
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130130
end
131131
end
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133-
mutable struct SimpleIntegrator3SstarOptions{Callback}
134-
callback::Callback # callbacks; used in Trixi.jl
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adaptive::Bool # whether the algorithm is adaptive; ignored
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dtmax::Float64 # ignored
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maxiters::Int # maximal number of time steps
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tstops::Vector{Float64} # tstops from https://diffeq.sciml.ai/v6.8/basics/common_solver_opts/#Output-Control-1; ignored
139-
end
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function SimpleIntegrator3SstarOptions(callback, tspan; maxiters = typemax(Int),
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kwargs...)
143-
SimpleIntegrator3SstarOptions{typeof(callback)}(callback, false, Inf, maxiters,
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[last(tspan)])
145-
end
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mutable struct SimpleIntegrator3Sstar{RealT <: Real, uType, Params, Sol, F, Alg,
148-
SimpleIntegrator3SstarOptions} <:
149-
AbstractTimeIntegrator
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SimpleIntegratorOptions} <: AbstractTimeIntegrator
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u::uType
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du::uType
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u_tmp1::uType
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sol::Sol # faked
160145
f::F # `rhs!` of the semidiscretization
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alg::Alg # SimpleAlgorithm3Sstar
162-
opts::SimpleIntegrator3SstarOptions
147+
opts::SimpleIntegratorOptions
163148
finalstep::Bool # added for convenience
164149
end
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166-
# Forward integrator.stats.naccept to integrator.iter (see GitHub PR#771)
167-
function Base.getproperty(integrator::SimpleIntegrator3Sstar, field::Symbol)
168-
if field === :stats
169-
return (naccept = getfield(integrator, :iter),)
170-
end
171-
# general fallback
172-
return getfield(integrator, field)
173-
end
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175151
function init(ode::ODEProblem, alg::SimpleAlgorithm3Sstar;
176152
dt, callback::Union{CallbackSet, Nothing} = nothing, kwargs...)
177153
u = copy(ode.u0)
@@ -183,9 +159,9 @@ function init(ode::ODEProblem, alg::SimpleAlgorithm3Sstar;
183159
integrator = SimpleIntegrator3Sstar(u, du, u_tmp1, u_tmp2, t, dt, zero(dt), iter,
184160
ode.p,
185161
(prob = ode,), ode.f, alg,
186-
SimpleIntegrator3SstarOptions(callback,
187-
ode.tspan;
188-
kwargs...), false)
162+
SimpleIntegratorOptions(callback,
163+
ode.tspan;
164+
kwargs...), false)
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190166
# initialize callbacks
191167
if callback isa CallbackSet
@@ -200,31 +176,6 @@ function init(ode::ODEProblem, alg::SimpleAlgorithm3Sstar;
200176
return integrator
201177
end
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203-
# Fakes `solve`: https://diffeq.sciml.ai/v6.8/basics/overview/#Solving-the-Problems-1
204-
function solve(ode::ODEProblem, alg::SimpleAlgorithm3Sstar;
205-
dt, callback = nothing, kwargs...)
206-
integrator = init(ode, alg, dt = dt, callback = callback; kwargs...)
207-
208-
# Start actual solve
209-
solve!(integrator)
210-
end
211-
212-
function solve!(integrator::SimpleIntegrator3Sstar)
213-
@unpack prob = integrator.sol
214-
215-
integrator.finalstep = false
216-
217-
@trixi_timeit timer() "main loop" while !integrator.finalstep
218-
step!(integrator)
219-
end # "main loop" timer
220-
221-
finalize_callbacks(integrator)
222-
223-
return TimeIntegratorSolution((first(prob.tspan), integrator.t),
224-
(prob.u0, integrator.u),
225-
integrator.sol.prob)
226-
end
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228179
function step!(integrator::SimpleIntegrator3Sstar)
229180
@unpack prob = integrator.sol
230181
@unpack alg = integrator
@@ -288,24 +239,13 @@ function step!(integrator::SimpleIntegrator3Sstar)
288239
end
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290241
# get a cache where the RHS can be stored
291-
get_du(integrator::SimpleIntegrator3Sstar) = integrator.du
292242
function get_tmp_cache(integrator::SimpleIntegrator3Sstar)
293243
(integrator.u_tmp1, integrator.u_tmp2)
294244
end
295245

296246
# some algorithms from DiffEq like FSAL-ones need to be informed when a callback has modified u
297247
u_modified!(integrator::SimpleIntegrator3Sstar, ::Bool) = false
298248

299-
# used by adaptive timestepping algorithms in DiffEq
300-
function set_proposed_dt!(integrator::SimpleIntegrator3Sstar, dt)
301-
integrator.dt = dt
302-
end
303-
304-
# Required e.g. for `glm_speed_callback`
305-
function get_proposed_dt(integrator::SimpleIntegrator3Sstar)
306-
return integrator.dt
307-
end
308-
309249
# stop the time integration
310250
function terminate!(integrator::SimpleIntegrator3Sstar)
311251
integrator.finalstep = true

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