Add methods for creating derivatives.

JuliaGNI · Dec 5, 2024 · c0d17f8 · c0d17f8
1 parent 02c617b
commit c0d17f8
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Showing 5 changed files with 32 additions and 18 deletions.
diff --git a/src/EulerLagrange.jl b/src/EulerLagrange.jl
@@ -29,13 +29,13 @@ module EulerLagrange
 
 
     export HamiltonianSystem
-    export hamiltonian, hamiltonian_variables
+    export hamiltonian, hamiltonian_variables, hamiltonian_derivatives
 
     include("hamiltonian.jl")
 
 
     export LagrangianSystem, DegenerateLagrangianSystem
-    export lagrangian, lagrangian_variables
+    export lagrangian, lagrangian_variables, lagrangian_derivatives
 
     include("lagrangian_common.jl")
     include("lagrangian.jl")

diff --git a/src/hamiltonian.jl b/src/hamiltonian.jl
@@ -13,6 +13,23 @@ function substitute_hamiltonian_variables(equs::NamedTuple, q, p)
     NamedTuple{keys(equs)}(Tuple(substitute_hamiltonian_variables(eq, q, p) for eq in equs))
 end
 
+
+function hamiltonian_variables(dimension::Int)
+    t = parameter(:t)
+    @variables (q(t))[1:dimension]
+    @variables (p(t))[1:dimension]
+    return (t,q,p)
+end
+
+function hamiltonian_derivatives(t, q, p)
+    Dt = Differential(t)
+    Dq = collect(Differential.(q))
+    Dp = collect(Differential.(p))
+
+    return (Dt, Dq, Dp)
+end
+
+
 """
     HamiltonianSystem
 """
@@ -32,9 +49,7 @@ struct HamiltonianSystem
         @variables Q[axes(q,1)]
         @variables P[axes(p,1)]
 
-        Dt = Differential(t)
-        Dq = collect(Differential.(q))
-        Dp = collect(Differential.(p))
+        Dt, Dq, Dp = hamiltonian_derivatives(t, q, p)
 
         Hs = dosimplify ? simplify(H) : H
 
@@ -90,13 +105,6 @@ function Base.show(io::IO, hsys::HamiltonianSystem)
     # end
 end
 
-function hamiltonian_variables(dimension::Int)
-    t = parameter(:t)
-    @variables (q(t))[1:dimension]
-    @variables (p(t))[1:dimension]
-    return (t,q,p)
-end
-
 
 function HODE(lsys::HamiltonianSystem; kwargs...)
     eqs = functions(lsys)

diff --git a/src/lagrangian.jl b/src/lagrangian.jl
@@ -23,9 +23,8 @@ struct LagrangianSystem
         @variables F[axes(x, 1)]
         @variables Λ[axes(v, 1)]
 
-        Dt = Differential(t)
-        Dx = collect(Differential.(x))
-        Dv = collect(Differential.(v))
+        Dt, Dx, Dv = lagrangian_derivatives(t, x, v)
+
         Dz = vcat(Dx,Dv)
         ẋ  = collect(Dt.(x))
         ṗ  = collect(Dt.(p))

diff --git a/src/lagrangian_common.jl b/src/lagrangian_common.jl
@@ -45,3 +45,11 @@ function lagrangian_variables(dimension::Int)
 
     return (t,x,v)
 end
+
+function lagrangian_derivatives(t, x, v)
+    Dt = Differential(t)
+    Dx = collect(Differential.(x))
+    Dv = collect(Differential.(v))
+
+    return (Dt, Dx, Dv)
+end
diff --git a/src/lagrangian_degenerate.jl b/src/lagrangian_degenerate.jl
@@ -23,9 +23,8 @@ struct DegenerateLagrangianSystem
         @variables F[axes(x, 1)]
         @variables Λ[axes(v, 1)]
 
-        Dt = Differential(t)
-        Dx = collect(Differential.(x))
-        Dv = collect(Differential.(v))
+        Dt, Dx, Dv = lagrangian_derivatives(t, x, v)
+
         ẋ  = collect(Dt.(x))
 
         K  = θ ⋅ v