Add Enzyme extension to make AbstractSensitivityAlgorithm inactive #1137
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Summary
Adds an Enzyme extension to SciMLBase to make
AbstractSensitivityAlgorithminactive during Enzyme differentiation.Problem
Currently, when sensitivity algorithms are passed to
ODEProblemconstructors (e.g.,ODEProblem(f, u0, tspan, p; sensealg=BacksolveAdjoint(autojacvec=EnzymeVJP()))), Enzyme fails with:This occurs because Enzyme tries to differentiate through the sensitivity algorithm object, which contains complex structures that Enzyme cannot handle.
See issue: SciML/SciMLSensitivity.jl#1225
Solution
This PR adds a proper Enzyme extension to SciMLBase with an
inactive_typerule:This is the correct location for this fix because:
AbstractSensitivityAlgorithmis defined in SciMLBaseChanges
ext/SciMLBaseEnzymeExt.jlwith the inactive type ruleTesting
The fix resolves the original issue where:
solve(prob, alg; sensealg=BacksolveAdjoint(...))worksODEProblem(f, u0, tspan, p; sensealg=BacksolveAdjoint(...))failsAfter this change, both work correctly with Enzyme differentiation.
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