# Errors when running a Universal Differential Equation (UDE)
**URL:** https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273
**Category:** New to Julia
**Tags:** ode, optimization, ad, lux
**Created:** [January 27, 2025, 6:54pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273 "2025-01-27T18:54:24Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@Ashima\_Kalathingal](https://discourse.julialang.org/u/Ashima_Kalathingal)
#### Post date: [January 27, 2025, 6:54pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/1 "2025-01-27T18:54:24Z")
Hello,
I am building a UDE as a part of my work in Julia. I am using the following example as reference
[https://docs.sciml.ai/Overview/stable/showcase/missing\_physics/](https://docs.sciml.ai/Overview/stable/showcase/missing_physics/)
Unfortunately I am getting a warning message and error during implementation. As I am new to this topic I am not able to understand where I am going wrong. The following is the code I am using
```julia
using OrdinaryDiffEq , SciMLSensitivity ,Optimization, OptimizationOptimisers,OptimizationOptimJL, LineSearches
using Statistics
using StableRNGs, JLD2, Lux, Zygote , Plots , ComponentArrays
# Set a random seed for reporoducible behaviour
rng = StableRNG(11)
# loading the training data
function find_discharge_end(Current_data,start=5)
for i in start:length(Current_data)
if abs(Current_data[i]) == 0
return i
end
end
return -1
end
# This below function finds the discharge current value at each C_rates
function current_val(Crate)
if Crate == "0p5C"
return 0.5*5.0
elseif Crate == "1C"
return 1.0*5.0
elseif Crate == "2C"
return 2.0*5.0
elseif Crate == "1p5C"
return 1.5*5.0
end
end
#training conditions
Crate1,Temp1 = "1C",10
Crate2,Temp2 = "0p5C",25
Crate3,Temp3 = "2C",0
Crate4,Temp4 = "1C",25
Crate5,Temp5 = "0p5C",0
Crate6,Temp6 = "2C",10
# Loading data
data_file = load("Datasets_ashima.jld2")["Datasets"]
data1 = data_file["$(Crate1)_T$(Temp1)"]
data2 = data_file["$(Crate2)_T$(Temp2)"]
data3 = data_file["$(Crate3)_T$(Temp3)"]
data4 = data_file["$(Crate4)_T$(Temp4)"]
data5 = data_file["$(Crate5)_T$(Temp5)"]
data6 = data_file["$(Crate6)_T$(Temp6)"]
# Finding the end of discharge index value and current value
n1,I1 = find_discharge_end(data1["current"]),current_val(Crate1)
n2,I2 = find_discharge_end(data2["current"]),current_val(Crate2)
n3,I3 = find_discharge_end(data3["current"]),current_val(Crate3)
n4,I4 = find_discharge_end(data4["current"]),current_val(Crate4)
n5,I5 = find_discharge_end(data5["current"]),current_val(Crate5)
n6,I6 = find_discharge_end(data6["current"]),current_val(Crate6)
t1,T1,T∞1 = data1["time"][2:n1],data1["temperature"][2:n1],data1["temperature"][1]
t2,T2,T∞2 = data2["time"][2:n2],data2["temperature"][2:n2],data2["temperature"][1]
t3,T3,T∞3 = data3["time"][2:n3],data3["temperature"][2:n3],data3["temperature"][1]
t4,T4,T∞4 = data4["time"][2:n4],data4["temperature"][2:n4],data4["temperature"][1]
t5,T5,T∞5 = data5["time"][2:n5],data5["temperature"][2:n5],data5["temperature"][1]
t6,T6,T∞6 = data6["time"][2:n6],data6["temperature"][2:n6],data6["temperature"][1]
# Defining the neural network
const NN = Lux.Chain(Lux.Dense(3,20,tanh),Lux.Dense(20,20,tanh),Lux.Dense(20,1)) # The const ensure faster execution and no accidental modification to the variable NN
# Get the initial parameters and state variables of the Model
para,st = Lux.setup(rng,NN)
const _st = st
# Defining the hybrid Model
function NODE_model!(du,u,p,t,T∞,I)
Cbat = 5*3600 # Battery capacity based on nominal voltage and energy in As
du[1] = -I/Cbat # To estimate the SOC of the battery
C₁ = -0.00153 # Unit is s-1
C₂ = 0.020306 # Unit is K/J
G = I*(NN([u[1],u[2],I],p,_st)[1][1]) # Input to the neural network is SOC, Cell temperature, current.
du[2] = (C₁*(u[2]-T∞)) + (C₂*G) # G is in W here
end
# Closure with known parameter
NODE_model1!(du,u,p,t) = NODE_model!(du,u,p,t,T∞1,I1)
NODE_model2!(du,u,p,t) = NODE_model!(du,u,p,t,T∞2,I2)
NODE_model3!(du,u,p,t) = NODE_model!(du,u,p,t,T∞3,I3)
NODE_model4!(du,u,p,t) = NODE_model!(du,u,p,t,T∞4,I4)
NODE_model5!(du,u,p,t) = NODE_model!(du,u,p,t,T∞5,I5)
NODE_model6!(du,u,p,t) = NODE_model!(du,u,p,t,T∞6,I6)
# Define the problem
prob1 = ODEProblem(NODE_model1!,[1.0,T∞1],(t1[1],t1[end]),para)
prob2 = ODEProblem(NODE_model2!,[1.0,T∞2],(t2[1],t2[end]),para)
prob3 = ODEProblem(NODE_model3!,[1.0,T∞3],(t3[1],t3[end]),para)
prob4 = ODEProblem(NODE_model4!,[1.0,T∞4],(t4[1],t4[end]),para)
prob5 = ODEProblem(NODE_model5!,[1.0,T∞5],(t5[1],t5[end]),para)
prob6 = ODEProblem(NODE_model6!,[1.0,T∞6],(t6[1],t6[end]),para)
# Function that predicts the state and calculates the loss
α = 1
function loss_NODE(θ)
N_dataset = 6
Solver = Tsit5()
if α%N_dataset ==0
_prob1 = remake(prob1,p=θ)
sol = Array(solve(_prob1,Solver,saveat=t1,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss1 = mean(abs2,T1.-sol[2,:])
return loss1
elseif α%N_dataset ==1
_prob2 = remake(prob2,p=θ)
sol = Array(solve(_prob2,Solver,saveat=t2,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss2 = mean(abs2,T2.-sol[2,:])
return loss2
elseif α%N_dataset ==2
_prob3 = remake(prob3,p=θ)
sol = Array(solve(_prob3,Solver,saveat=t3,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss3 = mean(abs2,T3.-sol[2,:])
return loss3
elseif α%N_dataset ==3
_prob4 = remake(prob4,p=θ)
sol = Array(solve(_prob4,Solver,saveat=t4,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss4 = mean(abs2,T4.-sol[2,:])
return loss4
elseif α%N_dataset ==4
_prob5 = remake(prob5,p=θ)
sol = Array(solve(_prob5,Solver,saveat=t5,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss5 = mean(abs2,T5.-sol[2,:])
return loss5
elseif α%N_dataset ==5
_prob6 = remake(prob6,p=θ)
sol = Array(solve(_prob6,Solver,saveat=t6,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss6 = mean(abs2,T6.-sol[2,:])
return loss6
end
end
# Defining a callback function to monitor the training process
plot_ = plot(framestyle = :box, legend = :none, xlabel = "Iteration",ylabel = "Loss (RMSE)",title = "Neural Network Training")
itera = 0
callback = function (state,l)
global α +=1
global itera +=1
colors_ = [:red,:blue,:green,:purple,:orange,:black]
println("RMSE Loss at iteration $(itera) is $(sqrt(l)) ")
scatter!(plot_,[itera],[sqrt(l)],markersize=4,markercolor = colors_[α%6+1])
display(plot_)
return false
end
# Training
adtype = Optimization.AutoZygote()
optf = Optimization.OptimizationFunction((x,k) -> loss_NODE(x),adtype)
optprob = Optimization.OptimizationProblem(optf,ComponentVector{Float64}(para)) # The component vector to ensure that parameters get a strucutred format
# Optimizing the parameters
res1 = Optimization.solve(optprob,OptimizationOptimisers.Adam(),callback=callback,maxiters = 500)
para_adam = res1.u
```
First comes the following warning message
```julia
Warning: Lux.apply(m::AbstractLuxLayer, x::AbstractArray{<:ReverseDiff.TrackedReal}, ps, st) input was corrected to Lux.apply(m::AbstractLuxLayer, x::ReverseDiff.TrackedArray}, ps, st).
│
│ 1. If this was not the desired behavior overload the dispatch on `m`.
│
│ 2. This might have performance implications. Check which layer was causing this problem using `Lux.Experimental.@debug_mode`.
└ @ LuxCoreArrayInterfaceReverseDiffExt C:\Users\Kalath_A\.julia\packages\LuxCore\8mVob\ext\LuxCoreArrayInterfaceReverseDiffExt.jl:10
```
Then after that error message pops up.
```julia
RMSE Loss at iteration 1 is 2.4709837988316155
ERROR: UndefVarError: `dλ` not defined in local scope
Suggestion: check for an assignment to a local variable that shadows a global of the same name.
Stacktrace:
[1] _adjoint_sensitivities(sol::ODESolution{…}, sensealg::QuadratureAdjoint{…}, alg::Tsit5{…}; t::Vector{…}, dgdu_discrete::Function, dgdp_discrete::Nothing, dgdu_continuous::Nothing, dgdp_continuous::Nothing, g::Nothing, abstol::Float64, reltol::Float64, callback::Nothing, kwargs::@Kwargs{…})
@ SciMLSensitivity C:\Users\Kalath_A\.julia\packages\SciMLSensitivity\RQ8Av\src\quadrature_adjoint.jl:402
[2] _adjoint_sensitivities
@ C:\Users\Kalath_A\.julia\packages\SciMLSensitivity\RQ8Av\src\quadrature_adjoint.jl:337 [inlined]
[3] #adjoint_sensitivities#63
@ C:\Users\Kalath_A\.julia\packages\SciMLSensitivity\RQ8Av\src\sensitivity_interface.jl:401 [inlined]
[4] (::SciMLSensitivity.var"#adjoint_sensitivity_backpass#323"{…})(Δ::ODESolution{…})
@ SciMLSensitivity C:\Users\Kalath_A\.julia\packages\SciMLSensitivity\RQ8Av\src\concrete_solve.jl:627
[5] ZBack
@ C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\chainrules.jl:212 [inlined]
[6] (::Zygote.var"#kw_zpullback#56"{…})(dy::ODESolution{…})
@ Zygote C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\chainrules.jl:238
[7] #295
@ C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\lib\lib.jl:205 [inlined]
[8] (::Zygote.var"#2169#back#297"{…})(Δ::ODESolution{…})
@ Zygote C:\Users\Kalath_A\.julia\packages\ZygoteRules\CkVIK\src\adjoint.jl:72
[9] #solve#51
@ C:\Users\Kalath_A\.julia\packages\DiffEqBase\R2Vjs\src\solve.jl:1038 [inlined]
[10] (::Zygote.Pullback{…})(Δ::ODESolution{…})
@ Zygote C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\interface2.jl:0
[11] #295
@ C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\lib\lib.jl:205 [inlined]
[12] (::Zygote.var"#2169#back#297"{…})(Δ::ODESolution{…})
@ Zygote C:\Users\Kalath_A\.julia\packages\ZygoteRules\CkVIK\src\adjoint.jl:72
[13] solve
@ C:\Users\Kalath_A\.julia\packages\DiffEqBase\R2Vjs\src\solve.jl:1028 [inlined]
[14] (::Zygote.Pullback{…})(Δ::ODESolution{…})
@ Zygote C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\interface2.jl:0
[15] loss_NODE
@ c:\Users\Kalath_A\OneDrive - University of Warwick\PhD\ML Notebooks\Neural ODE\Julia\T Mixed\With Qgen multiplied with I\updated_code.jl:128 [inlined]
[16] (::Zygote.Pullback{Tuple{typeof(loss_NODE), ComponentVector{Float64, Vector{…}, Tuple{…}}}, Any})(Δ::Float64)
@ Zygote C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\interface2.jl:0
[17] #13
@ c:\Users\Kalath_A\OneDrive - University of Warwick\PhD\ML Notebooks\Neural ODE\Julia\T Mixed\With Qgen multiplied with I\updated_code.jl:169 [inlined]
[18] (::Zygote.var"#78#79"{Zygote.Pullback{Tuple{…}, Tuple{…}}})(Δ::Float64)
@ Zygote C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\interface.jl:91
[19] withgradient(::Function, ::ComponentVector{Float64, Vector{Float64}, Tuple{Axis{…}}}, ::Vararg{Any})
@ Zygote C:\Users\Kalath_A\.julia\packages\Zygote\TWpme\src\compiler\interface.jl:213
[20] value_and_gradient
@ C:\Users\Kalath_A\.julia\packages\DifferentiationInterface\TtV2Z\ext\DifferentiationInterfaceZygoteExt\DifferentiationInterfaceZygoteExt.jl:118 [inlined]
[21] value_and_gradient!(f::Function, grad::ComponentVector{…}, prep::DifferentiationInterface.NoGradientPrep, backend::AutoZygote, x::ComponentVector{…}, contexts::DifferentiationInterface.Constant{…})
@ DifferentiationInterfaceZygoteExt C:\Users\Kalath_A\.julia\packages\DifferentiationInterface\TtV2Z\ext\DifferentiationInterfaceZygoteExt\DifferentiationInterfaceZygoteExt.jl:143
[22] (::OptimizationZygoteExt.var"#fg!#16"{…})(res::ComponentVector{…}, θ::ComponentVector{…})
@ OptimizationZygoteExt C:\Users\Kalath_A\.julia\packages\OptimizationBase\gvXsf\ext\OptimizationZygoteExt.jl:53
[23] macro expansion
@ C:\Users\Kalath_A\.julia\packages\OptimizationOptimisers\xC7Ic\src\OptimizationOptimisers.jl:101 [inlined]
[24] macro expansion
@ C:\Users\Kalath_A\.julia\packages\Optimization\6Asog\src\utils.jl:32 [inlined]
[25] __solve(cache::OptimizationCache{…})
@ OptimizationOptimisers C:\Users\Kalath_A\.julia\packages\OptimizationOptimisers\xC7Ic\src\OptimizationOptimisers.jl:83
[26] solve!(cache::OptimizationCache{…})
@ SciMLBase C:\Users\Kalath_A\.julia\packages\SciMLBase\3fgw8\src\solve.jl:187
[27] solve(::OptimizationProblem{…}, ::Optimisers.Adam; kwargs::@Kwargs{…})
@ SciMLBase C:\Users\Kalath_A\.julia\packages\SciMLBase\3fgw8\src\solve.jl:95
[28] top-level scope
@ c:\Users\Kalath_A\OneDrive - University of Warwick\PhD\ML Notebooks\Neural ODE\Julia\T Mixed\With Qgen multiplied with I\updated_code.jl:173
Some type information was truncated. Use `show(err)` to see complete types.
```
Does anyone know why this warning and error message pops up? I am following the UDE example which I mentioned earlier as a reference. The example works well without any errors. In the example Vern7() is used to solve the ODE. I tried that too. But the same warning and error pops up. I am reading on some theory to see if learning more about Automatic Differentiation (AD) would help in debugging this.
Any help would be much appreciated
---
### Author:  [@lupemba](https://discourse.julialang.org/u/lupemba)
#### Post date: [January 28, 2025, 12:56pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/2 "2025-01-28T12:56:09Z")
> [@Ashima\_Kalathingal](#):
>
> ```julia
> global α +=1
> global itera +=1
>
> ```
I don’t now anything about UDEs but this part looks like it could cause some issues. Do the examples really use global variables like that?
You might want to use a loop instead of `global itera +=1` and maybe have `α` as an input to the loss function.
The code have many global variables in general. This could be the cause of the issues.
---
### Author:  [@Ashima\_Kalathingal](https://discourse.julialang.org/u/Ashima_Kalathingal)
#### Post date: [January 28, 2025, 7:39pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/3 "2025-01-28T19:39:02Z")
I updated the code such that I am not defining any global variables.
```julia
function loss_NODE(θ)
N_dataset = 6
Solver = Tsit5()
α = length(losses) + 1
if α%N_dataset ==0
_prob1 = remake(prob1,p=θ)
sol = Array(solve(_prob1,Solver,saveat=t1,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss1 = mean(abs2,T1.-sol[2,:])
return loss1
elseif α%N_dataset ==1
_prob2 = remake(prob2,p=θ)
sol = Array(solve(_prob2,Solver,saveat=t2,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss2 = mean(abs2,T2.-sol[2,:])
return loss2
elseif α%N_dataset ==2
_prob3 = remake(prob3,p=θ)
sol = Array(solve(_prob3,Solver,saveat=t3,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss3 = mean(abs2,T3.-sol[2,:])
return loss3
elseif α%N_dataset ==3
_prob4 = remake(prob4,p=θ)
sol = Array(solve(_prob4,Solver,saveat=t4,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss4 = mean(abs2,T4.-sol[2,:])
return loss4
elseif α%N_dataset ==4
_prob5 = remake(prob5,p=θ)
sol = Array(solve(_prob5,Solver,saveat=t5,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss5 = mean(abs2,T5.-sol[2,:])
return loss5
elseif α%N_dataset ==5
_prob6 = remake(prob6,p=θ)
sol = Array(solve(_prob6,Solver,saveat=t6,abstol=1e-6,reltol=1e-6,sensealg = QuadratureAdjoint(autojacvec = ReverseDiffVJP(true))))
loss6 = mean(abs2,T6.-sol[2,:])
return loss6
end
end
# Defining a callback function to monitor the training process
plot_ = plot(framestyle = :box, legend = :none, xlabel = "Iteration",ylabel = "Loss (RMSE)",title = "Neural Network Training")
losses = Float64[]
callback = function (state,l)
push!(losses,l)
α = length(losses)
itera = length(losses)
colors_ = [:red,:blue,:green,:purple,:orange,:black]
println("RMSE Loss at iteration $(itera) is $(sqrt(l)) ")
scatter!(plot_,[itera],[sqrt(l)],markersize=4,markercolor = colors_[α%6+1])
display(plot_)
return false
end
# Training
adtype = Optimization.AutoZygote()
optf = Optimization.OptimizationFunction((x,p) -> loss_NODE(x),adtype)
optprob = Optimization.OptimizationProblem(optf,ComponentVector{Float64}(para)) # The component vector to ensure that parameters get a strucutred format
# Optimizing the parameters
res1 = Optimization.solve(optprob,OptimizationOptimisers.Adam(),callback=callback,maxiters = 500)
para_adam = res1.u
```
This is the updated code. I defined the a variable named `losses` to keep track of iterations. But the same error occurs.
```julia
ERROR: UndefVarError: `dλ` not defined in local scope
Suggestion: check for an assignment to a local variable that shadows a global of the same name.
```
I wonded what is `dλ`. I cannot find any info on that.
---
### Author:  [@lupemba](https://discourse.julialang.org/u/lupemba)
#### Post date: [January 29, 2025, 9:57am UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/4 "2025-01-29T09:57:28Z")
The error comes from [SciMLSensitivity.jl/src/quadrature\_adjoint.jl at f9e7b58ce6d9c8c20ac96510d1a67d91f0f5bba9 · SciML/SciMLSensitivity.jl · GitHub](https://github.com/SciML/SciMLSensitivity.jl/blob/f9e7b58ce6d9c8c20ac96510d1a67d91f0f5bba9/src/quadrature_adjoint.jl#L402)
I think the best approach is to create an issues on the github repository and ask them directly why it is not working.
Other tips;
- The examples is still using global variables. I would consider all variables that are not passed to a function as input or constructed inside the function global variables. This includes variables like `prob1` and `losses`.
- It will be easier to support you if you provide a minimal working example (MWE). This is a small example that produces the error and that others are able to run on their own computer. Your current example can not be run without the data.
---
### Author:  [@Ashima\_Kalathingal](https://discourse.julialang.org/u/Ashima_Kalathingal)
#### Post date: [January 29, 2025, 10:41pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/5 "2025-01-29T22:41:17Z")
Thank you for your suggestions. I will provide a minimal working example (MWE) as another post to see if others also have same issue as me 🙂
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [January 31, 2025, 9:58am UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/6 "2025-01-31T09:58:24Z")
I’ll need a reproducer for this if it’s hitting the branch for handling `dt=0`. It’s a very odd case.
---
### Author:  [@Ashima\_Kalathingal](https://discourse.julialang.org/u/Ashima_Kalathingal)
#### Post date: [February 3, 2025, 9:10pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/7 "2025-02-03T21:10:05Z")
Thank you for your replies. I was able to correct the following error
```julia
ERROR: UndefVarError: `dλ` not defined in local scope
Suggestion: check for an assignment to a local variable that shadows a global of the same name.
```
In my dataset the variable time was not strictly increasing. When I corrected it, the error stopped showing.
But this following warning is still showing. I don’t know the cause of it yet
```julia
Warning: Lux.apply(m::AbstractLuxLayer, x::AbstractArray{<:ReverseDiff.TrackedReal}, ps, st) input was corrected to Lux.apply(m::AbstractLuxLayer, x::ReverseDiff.TrackedArray}, ps, st).
│
│ 1. If this was not the desired behavior overload the dispatch on `m`.
│
│ 2. This might have performance implications. Check which layer was causing this problem using `Lux.Experimental.@debug_mode`
```
---
### Author:  [@ChrisRackauckas](https://discourse.julialang.org/u/ChrisRackauckas)
#### Post date: [February 6, 2025, 12:28am UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/8 "2025-02-06T00:28:03Z")
Can you open an issue with an MWE? It sounds like we implicitly assume that your `saveat` is given monotonically in the right order, which is violated in your case. That should get a validation at least to check and error if the user violated that condition. I don’t think I ever validated that since I never thought to run an example where the data wasn’t in order 😅
---
### Author:  [@Ashima\_Kalathingal](https://discourse.julialang.org/u/Ashima_Kalathingal)
#### Post date: [February 8, 2025, 12:50pm UTC](https://discourse.julialang.org/t/errors-when-running-a-universal-differential-equation-ude/125273/9 "2025-02-08T12:50:58Z")
Okay I will 😃 👍