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Fixes RK4 and AB3 timesteppers for sol<:AbstractArray #106

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Jan 27, 2019
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Fixes RK4 and AB3 timesteppers for sol<:AbstractArray #106

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45 changes: 29 additions & 16 deletions src/timesteppers.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -208,7 +208,7 @@ function RK4substeps!(sol, cl, ts, eq, v, p, g, t, dt)
nothing
end

function RK4substeps!(sol::AbstractArray{T}, cl, ts, eq, v, p, g) where T<:AbstractArray
function RK4substeps!(sol::AbstractArray{T}, cl, ts, eq, v, p, g, t, dt) where T<:AbstractArray
# Substep 1
eq.calcN!(ts.RHS₁, sol, t, cl, v, p, g)
addlinearterm!.(ts.RHS₁, eq.L, sol)
Expand Down Expand Up @@ -448,39 +448,52 @@ function FilteredAB3TimeStepper(eq; filterkwargs...)
FilteredAB3TimeStepper(getfield.(Ref(ts), fieldnames(typeof(ts)))..., filter)
end


function stepforward!(sol, cl, ts::AB3TimeStepper, eq, v, p, g)
eq.calcN!(ts.RHS, sol, cl.t, cl, v, p, g)
@. ts.RHS += eq.L*sol # Add linear term to RHS

function AB3update!(sol, ts, cl)
if cl.step < 3 # forward Euler steps to initialize AB3
@. sol += cl.dt*ts.RHS # Update
else # Otherwise, stepforward with 3rd order Adams Bashforth:
@. sol += cl.dt*(ab3h1*ts.RHS - ab3h2*ts.RHS₋₁ + ab3h3*ts.RHS₋₂)
end
nothing
end

function AB3update!(sol, ts::FilteredAB3TimeStepper, cl)
if cl.step < 3 # forward Euler steps to initialize AB3
@. sol = ts.filter*(sol + cl.dt*ts.RHS) # Update
else # Otherwise, stepforward with 3rd order Adams Bashforth:
@. sol = ts.filter*(sol + cl.dt*(ab3h1*ts.RHS - ab3h2*ts.RHS₋₁ + ab3h3*ts.RHS₋₂))
end
nothing
end

function stepforward!(sol, cl, ts::AB3TimeStepper, eq, v, p, g)
eq.calcN!(ts.RHS, sol, cl.t, cl, v, p, g)
addlinearterm!(ts.RHS, eq.L, sol)
AB3update!(sol, ts, cl)
cl.t += cl.dt
cl.step += 1

@. ts.RHS₋₂ = ts.RHS₋₁ # Store
@. ts.RHS₋₁ = ts.RHS # ... previous values of RHS
nothing
end

function stepforward!(sol::AbstractArray{T}, cl, ts::AB3TimeStepper, eq, v, p, g) where T<:AbstractArray
eq.calcN!(ts.RHS, sol, cl.t, cl, v, p, g)
addlinearterm!.(ts.RHS, eq.L, sol)
AB3update!(sol, ts, cl)
cl.t += cl.dt
cl.step += 1
@. ts.RHS₋₂ = ts.RHS₋₁ # Store
@. ts.RHS₋₁ = ts.RHS # ... previous values of RHS
nothing
end

function stepforward!(sol, cl, ts::FilteredAB3TimeStepper, eq, v, p, g)
eq.calcN!(ts.RHS, sol, cl.t, cl, v, p, g)
@. ts.RHS += eq.L*sol # Add linear term to RHS

if cl.step < 3 # forward Euler steps to initialize AB3
@. sol = ts.filter*(sol + cl.dt*ts.RHS) # Update
else # Otherwise, stepforward with 3rd order Adams Bashforth:
@. sol = ts.filter*(sol + cl.dt*(ab3h1*ts.RHS - ab3h2*ts.RHS₋₁ + ab3h3*ts.RHS₋₂))
end

addlinearterm!(ts.RHS, eq.L, sol)
AB3update!(sol, ts, cl)
cl.t += cl.dt
cl.step += 1

@. ts.RHS₋₂ = ts.RHS₋₁ # Store
@. ts.RHS₋₁ = ts.RHS # ... previous values of RHS
nothing
Expand Down