Issue with SS.solve using DynamicSS method in SteadyStateDiffEq

Bill_Holmes
Thu, 06 Nov 2025 16:05:36 +0000
Modelling & Simulations

I have a quick question about using SteadyStateDiffEq.jl. I am getting error behavior when trying to use the DynamicSS method (following Steady State Solvers · DifferentialEquations.jl). Below is a MWE. I 1) define a standard ODEProblem, 2) use this to define a SteadyStateProblem, 3) solve using DynamicSS. Attempting to solve with the DynamicSS() yields the error shown below. Using the SSRootFind() method works (though this has some issues with my specific use case and so I want DynamicSS).

This seems like I’m making some sort of syntax / call error, but the docs / examples on this are a little thin. Can anyone point me to the correct usage?

I am using Julia 1.12.1 with the following package information (tried with 1.11.5, 1.11.7, 1.10.8 using clean environments also, same error). This is a clean environment with only these directly added.

using Pkg
Pkg.activate("./Local_Env")

import SteadyStateDiffEq as SS
import DifferentialEquations as DE

function ode!(du, u, p, t)
    rr, dd = p
    du[1] = rr - dd * u[1]
end

tspan = (0.0, 100.0);
u0 = [1.0];
params = [2.0, 0.5];

odeprob_tmp = DE.ODEProblem(ode!, u0, tspan, params);
sol_test = DE.solve(odeprob_tmp, DE.Rodas5P()); # ODEProb verified

ssprob = SS.SteadyStateProblem(odeprob_tmp);

sol = SS.solve(ssprob, SS.DynamicSS(DE.Rodas5P())); ## Fails with error.

sol = SS.solve(ssprob, SS.SSRootfind());# Works as expected

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