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[deps] | ||
CriticalTransitions = "251e6cd3-3112-48a5-99dd-66efcfd18334" | ||
ModelingToolkit = "961ee093-0014-501f-94e3-6117800e7a78" | ||
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[compat] | ||
Documenter = "^1.4.1" |
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# System setup - FitzHugh-Nagumo model | ||
p = [1.0, 3.0, 1.0, 1.0, 1.0, 0.0] # Parameters (ϵ, β, α, γ, κ, I) | ||
σ = 0.2 # noise strength | ||
sys = CoupledSDEs(fitzhugh_nagumo, zeros(2), p; noise_strength=σ) | ||
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A = inv(covariance_matrix(sys)) | ||
T, N = 2.0, 100 | ||
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x_i = SA[sqrt(2 / 3), sqrt(2 / 27)] | ||
x_f = SA[0.0, 0.0] | ||
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path = reduce(hcat, range(x_i, x_f; length=N)) | ||
time = range(0.0, T; length=N) | ||
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b(x) = drift(sys, x) | ||
b(x[:, 2]) | ||
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using DynamicalSystemsBase | ||
b.(StateSpaceSet(path')) | ||
x = deepcopy(path) | ||
function mod!(x) | ||
for i in 1:size(x)[2] | ||
x[:, i] .= b(x[:, i]) | ||
end | ||
using CriticalTransitions | ||
using Plots | ||
using BenchmarkTools | ||
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const λ = 3 / 1.21 * 2 / 295 | ||
const ω0 = 1.000 | ||
const ω = 1.000 | ||
const γ = 1 / 295 | ||
const η = 0 | ||
const α = -1 | ||
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function fu(u, v) | ||
return (-4 * γ * ω * u - 2 * λ * v - 4 * (ω0 - ω^2) * v - 3 * α * v * (u^2 + v^2)) / | ||
(8 * ω) | ||
end | ||
function fv(u, v) | ||
return (-4 * γ * ω * v - 2 * λ * u + 4 * (ω0 - ω^2) * u + 3 * α * u * (u^2 + v^2)) / | ||
(8 * ω) | ||
end | ||
stream(u, v) = Point2f(fu(u, v), fv(u, v)) | ||
dfvdv(u, v) = (-4 * γ * ω + 6 * α * u * v) / (8 * ω) | ||
dfudu(u, v) = (-4 * γ * ω - 6 * α * u * v) / (8 * ω) | ||
dfvdu(u, v) = (-2 * λ + 4 * (ω0 - ω^2) + 9 * α * u^2 + 3 * α * v^2) / (8 * ω) | ||
dfudv(u, v) = (-2 * λ - 4 * (ω0 - ω^2) - 3 * α * u^2 - 9 * α * v^2) / (8 * ω) | ||
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Nt = 500 # number of discrete time steps | ||
s = collect(range(0; stop=1, length=Nt)) | ||
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xa = [-0.0208, 0.0991] | ||
xb = -xa | ||
xsaddle = [0.0, 0.0] | ||
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# Initial trajectory | ||
xx = @. (xb[1] - xa[1]) * s + xa[1] + 4 * s * (1 - s) * xsaddle[1] | ||
yy = @. (xb[2] - xa[2]) * s + xa[2] + 4 * s * (1 - s) * xsaddle[2] + 0.01 * sin(2π * s) | ||
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function H_x(x, p) # ℜ² → ℜ² | ||
u, v = eachrow(x) | ||
pu, pv = eachrow(p) | ||
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H_u = @. pu * dfudu(u, v) + pv * dfvdu(u, v) | ||
H_v = @. pu * dfudv(u, v) + pv * dfvdv(u, v) | ||
return Matrix([H_u H_v]') | ||
end | ||
function H_p(x, p) # ℜ² → ℜ² | ||
u, v = eachrow(x) | ||
pu, pv = eachrow(p) | ||
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H_pu = @. pu + fu(u, v) | ||
H_pv = @. pv + fv(u, v) | ||
return Matrix([H_pu H_pv]') | ||
end | ||
x = deepcopy(path) | ||
function mod1!(sys, x) | ||
for i in 1:size(x)[2] | ||
x[:, i] .= sys.integ.f(x[:, i], sys.p0, 0) | ||
end | ||
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sys_m = SgmamSystem(H_x, H_p) | ||
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x_init_m = Matrix([xx yy]') | ||
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function KPO_SA(x, p, t) | ||
u, v = x | ||
return SA[fu(u, v), fv(u, v)] | ||
end | ||
function mod2!(sys, x) | ||
for i in 1:size(x)[2] | ||
x[:, i] = sys.integ.f(x[:, i], sys.p0, 0) | ||
end | ||
function KPO(x, p, t) | ||
u, v = x | ||
return [fu(u, v), fv(u, v)] | ||
end | ||
x = deepcopy(path) | ||
@benchmark mod!($x) | ||
x = deepcopy(path) | ||
@benchmark mod1!($sys, $x) | ||
x = deepcopy(path) | ||
@benchmark mod2!($sys, $x) | ||
ds = CoupledSDEs(KPO, zeros(2), ()) | ||
ds_sa = CoupledSDEs(KPO_SA, zeros(2), ()) | ||
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using ModelingToolkit | ||
@independent_variables t | ||
D = Differential(t) | ||
sts = @variables u(t) v(t) | ||
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eqs = [ | ||
D(u) ~ fu(u, v), | ||
D(v) ~ fv(u, v) | ||
] | ||
@named sys1 = System(eqs, t) | ||
sys1 = structural_simplify(sys1) | ||
prob = ODEProblem(sys1, sts .=> zeros(2), (0.0, 100.0), (); jac=true) | ||
ds = CoupledODEs(prob) | ||
jac = jacobian(ds) | ||
jac([1,1], (), 0.0) | ||
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sgSys′ = SgmamSystem(ds); | ||
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p_r = rand(2, Nt) | ||
sgSys′.H_x(x_init_m, p_r) ≈ sys_m.H_x(x_init_m, p_r) | ||
sgSys′.H_p(x_init_m, p_r) ≈ sys_m.H_p(x_init_m, p_r) | ||
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@btime sgSys′.H_x($x_init_m, $p_r) # 118.600 μs (5001 allocations: 281.38 KiB) | ||
@btime sys_m.H_x($x_init_m, $p_r) # 5.333 μs (4 allocations: 24.00 KiB) | ||
@btime sgSys′.H_p($x_init_m, $p_r) # 66.200 μs (2001 allocations: 164.19 KiB) | ||
@btime sys_m.H_p($x_init_m, $p_r) # 5.083 μs (4 allocations: 24.00 KiB) |