Fix ChainRules codegen problem

examples/ode.jl

@@ -0,0 +1,46 @@
+using ADTypes
+using DifferentiationInterface
+using ModelingToolkit, DifferentialEquations
+using TaylorDiff, ForwardDiff
+using Enzyme, Zygote, ReverseDiff
+using SciMLSensitivity
+
+@parameters a
+@variables t x1(t)
+D = Differential(t)
+states = [x1]
+parameters = [a]
+
+@named pre_model = ODESystem([D(x1) ~ a * x1], t, states, parameters)
+model = structural_simplify(pre_model)
+
+ic = Dict(x1 => 1.0)
+p_true = Dict(a => 2.0)
+
+problem = ODEProblem{true, SciMLBase.FullSpecialize}(model, ic, [0.0, 1.0], p_true)
+soln = ModelingToolkit.solve(problem, Tsit5(), abstol = 1e-12, reltol = 1e-12)
+display(soln(0.5, idxs = [x1]))
+
+function different_time(new_ic, new_params, new_t)
+    #newprob = ODEProblem{true, SciMLBase.FullSpecialize}(model, new_ic, [0.0, new_t*2], new_params)
+    #newprob = remake(problem, u0=new_ic, tspan = [0.0, new_t], p = new_params)
+    newprob = remake(problem, u0 = new_ic, tspan = [0.0, new_t], p=new_params)
+    newprob = remake(newprob, u0 = typeof(new_t).(newprob.u0))
+    new_soln = ModelingToolkit.solve(newprob, Tsit5(), abstol = 1e-12, reltol = 1e-12)
+    return (soln(new_t, idxs = [x1]))
+end
+
+function just_t(new_t)
+    return different_time(ic, p_true, new_t)[1]
+end
+display(different_time(ic, p_true, 2e-5))
+display(just_t(0.5))
+
+
+#display(ForwardDiff.derivative(just_t,1.0))
+display(TaylorDiff.derivative(just_t,1.0,1))  #isnan error
+#display(value_and_gradient(just_t, AutoForwardDiff(), 1.0))
+#display(value_and_gradient(just_t, AutoReverseDiff(), 1.0))
+#display(value_and_gradient(just_t, AutoEnzyme(Enzyme.Reverse), 1.0))
+#display(value_and_gradient(just_t, AutoEnzyme(Enzyme.Forward), 1.0))
+#display(value_and_gradient(just_t, AutoZygote(), 1.0))

src/codegen.jl

@@ -4,20 +4,24 @@ using Symbolics: @variables
 using SymbolicUtils, SymbolicUtils.Code
 using SymbolicUtils: Pow
 
-dummy = (NoTangent(), 1)
-@variables z
-for func in (+, -, deg2rad, rad2deg,
+func_list = (
+    +, -, deg2rad, rad2deg,
     sinh, cosh, tanh,
     asin, acos, atan, asec, acsc, acot,
     log, log10, log1p, log2,
     asinh, acosh, atanh, asech, acsch,
     acoth,
     abs, sign)
+
+dummy = (NoTangent(), 1)
+@variables z
+for func in func_list
     F = typeof(func)
     # base case
     @eval function (op::$F)(t::TaylorScalar{T, 2}) where {T}
         t0, t1 = value(t)
-        TaylorScalar{T, 2}(frule((NoTangent(), t1), op, t0))
+        f0, f1 = frule((NoTangent(), t1), op, t0)
+        TaylorScalar{T, 2}(f0, zero_tangent(f0) + f1)
     end
     der = frule(dummy, func, z)[2]
     term, raiser = der isa Pow && der.exp == -1 ? (der.base, raiseinv) : (der, raise)
@@ -28,8 +32,9 @@ for func in (+, -, deg2rad, rad2deg,
         quote
             $(Expr(:meta, :inline))
             z = TaylorScalar{T, N - 1}(t)
-            df = $der_expr
-            $$raiser($f(value(t)[1]), df, t)
+            f0 = $f(value(t)[1])
+            df = zero_tangent(f0) + $der_expr
+            $$raiser(f0, df, t)
         end
     end
 end

src/primitive.jl

@@ -151,8 +151,13 @@ for R in (Integer, Real)
         ex = :($ex; TaylorScalar($([Symbol('u', i) for i in 1:N]...)))
         return :(@inbounds $ex)
     end
+    @eval function ^(a::S, t::TaylorScalar{T, N}) where {S <: $R, T, N}
+        exp(t * log(a))
+    end
 end
 
+^(t::TaylorScalar, s::TaylorScalar) = exp(s * log(t))
+
 @generated function raise(f::T, df::TaylorScalar{T, M},
         t::TaylorScalar{T, N}) where {T, M, N} # M + 1 == N
     return quote

src/scalar.jl

@@ -90,6 +90,16 @@ function promote_rule(::Type{TaylorScalar{T, N}},
     TaylorScalar{promote_type(T, S), N}
 end
 
-function Base.AbstractFloat(x::TaylorScalar{T, N}) where {T, N}
-    TaylorScalar{Float64, N}(convert(NTuple{N, Float64}, x.value))
+function (::Type{F})(x::TaylorScalar{T, N}) where {T, N, F <: AbstractFloat}
+    F(primal(x))
+end
+
+Base.nextfloat(x::TaylorScalar{T, N}) where {T, N} = TaylorScalar{T, N}(ntuple(i -> i == 1 ? nextfloat(value(x)[i]) : value(x)[i], N))
+
+Base.prevfloat(x::TaylorScalar{T, N}) where {T, N} = TaylorScalar{T, N}(ntuple(i -> i == 1 ? prevfloat(value(x)[i]) : value(x)[i], N))
+
+const UNARY_PREDICATES = Symbol[:isinf, :isnan, :isfinite, :iseven, :isodd, :isreal, :isinteger]
+
+for pred in UNARY_PREDICATES
+    @eval Base.$(pred)(x::TaylorScalar) = $(pred)(primal(x))
 end

test/primitive.jl

@@ -2,7 +2,7 @@ using FiniteDifferences
 
 @testset "No derivative or linear" begin
     some_number, another_number = 1.9, 2.6
-    for f in (+, -, zero, one, adjoint, conj, deg2rad, rad2deg), order in (2,)
+    for f in (+, -, zero, one, adjoint, conj, deg2rad, rad2deg, abs, sign), order in (2,)
         @test derivative(f, some_number, order) ≈ 0.0
     end
     for f in (+, -, <, <=, >, >=, ==), order in (2,)