Allow Dt as alternative keyword in trajectory (#173)

* Allow `Dt` in `trajectory`

* increase accuracy of poincare tests

* further increase poincare map accuracy

Author: Datseris

CHANGELOG.md

@@ -1,6 +1,9 @@
+# v3.2.0
+The keyword `Dt` can now be used instead of `Δt` in `trajectory` if access to unicode isn't available.
+
 # v3.1.0
 New error checking functionality added via `successful_step`. Returns `true` if the last `step!` call to `ds` was successful, `false` otherwise.
-For continuous time systems this uses DifferentialEquations.jl error checking,for discrete time it checks if any variable is `Inf` or `NaN`. Defaults to `true` for other types.   
+For continuous time systems this uses DifferentialEquations.jl error checking,for discrete time it checks if any variable is `Inf` or `NaN`. Defaults to `true` for other types.
 
 # v3.0
 

Project.toml

@@ -1,7 +1,7 @@
 name = "DynamicalSystemsBase"
 uuid = "6e36e845-645a-534a-86f2-f5d4aa5a06b4"
 repo = "https://github.com/JuliaDynamics/DynamicalSystemsBase.jl.git"
-version = "3.1.2"
+version = "3.2.0"
 
 [deps]
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"

src/core/trajectory.jl

@@ -14,7 +14,8 @@ The returned time vector is `t = (t0+Ttr):Δt:(t0+Ttr+T)`.
 ## Keyword arguments
 
 * `Δt`:  Time step of value output. For discrete time systems it must be an integer.
-  Defaults to `0.1` for continuous and `1` for discrete time systems.
+  Defaults to `0.1` for continuous and `1` for discrete time systems. If you don't
+  have access to unicode, the keyword `Dt` can be used instead.
 * `Ttr = 0`: Transient time to evolve the initial state before starting saving states.
 * `t0 = initial_time(ds)`: Starting time.
 * `save_idxs::AbstractVector{Int}`: Which variables to output in `X` (by default all).
@@ -31,7 +32,9 @@ function trajectory(ds::DynamicalSystem, T, u0 = initial_state(ds);
     end
 end
 
-function trajectory_discrete(ds, T; Δt::Integer = 1, Ttr::Integer = 0, accessor = nothing)
+function trajectory_discrete(ds, T;
+        Dt::Integer = 1, Δt::Integer = Dt, Ttr::Integer = 0, accessor = nothing
+    )
     ET = eltype(current_state(ds))
     t0 = current_time(ds)
     tvec = (t0+Ttr):Δt:(t0+T+Ttr)
@@ -55,7 +58,7 @@ function trajectory_discrete(ds, T; Δt::Integer = 1, Ttr::Integer = 0, accessor
     return StateSpaceSet(data), tvec
 end
 
-function trajectory_continuous(ds, T; Δt = 0.1, Ttr = 0.0, accessor = nothing)
+function trajectory_continuous(ds, T; Dt = 0.1, Δt = Dt, Ttr = 0.0, accessor = nothing)
     D = dimension(ds)
     t0 = current_time(ds)
     tvec = (t0+Ttr):Δt:(t0+T+Ttr)

test/poincare.jl

@@ -36,7 +36,7 @@ plane2 = gis_plane(μ)
 function poincare_tests(ds, pmap, plane)
     P, t = trajectory(pmap, 10)
     reinit!(ds)
-    P2 = poincaresos(ds, plane, 100)
+    P2 = poincaresos(ds, plane, 100; rootkw = (xrtol = 1e-12, atol = 1e-12))
     @test length(P) == 11
     @test P[1] == P2[1]
     @test length(P2) > 1
@@ -57,13 +57,14 @@ end
     rule = !IIP ? gissinger_rule : gissinger_rule_iip
     ds = CoupledODEs(rule, recursivecopy(u0), p)
     plane = P == 1 ? plane1 : plane2
-    pmap = PoincareMap(ds, plane)
+    pmap = PoincareMap(ds, plane; rootkw = (xrtol = 1e-12, atol = 1e-12))
     u0pmap = recursivecopy(current_state(pmap))
     test_dynamical_system(pmap, u0pmap, p;
     idt=true, iip=IIP, test_trajectory = true,
     test_init_state_equiv=false, u0init = initial_state(pmap))
-    # Specific poincare map tests here:
-    poincare_tests(ds, pmap, plane)
+    @testset "specific poincare" begin
+        poincare_tests(ds, pmap, plane)
+    end
 end
 
 @testset "set_parameter works" begin
@@ -79,7 +80,7 @@ end
     plane = (1, 0.0)
     ds = CoupledODEs(lorenz_rule, recursivecopy(u0), p)
 
-    pmap = PoincareMap(ds, plane)
+    pmap = PoincareMap(ds, plane; rootkw = (xrtol = 1e-12, atol = 1e-12))
     P, t = trajectory(pmap, 10)
     @test all(x -> abs(x) < 1e-6, P[:, 1])
 

test/test_system_function.jl

@@ -123,7 +123,7 @@ function test_dynamical_system(ds, u0, p0; idt, iip,
                 @test X[1] == u0
 
                 prev_u0 = deepcopy(current_state(ds))
-                Y, t2 = trajectory(ds, 3, nothing; Δt = 1)
+                Y, t2 = trajectory(ds, 3, nothing; Dt = 1)
                 @test Y[1] ≈ prev_u0 atol=1e-6
                 @test t2[1] > t[end]