JuliaDiff / JuliaDiff/ForwardDiff.jl
jacobian with StaticArray always uses autogenerated Tag
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Description
It doesn't seem to be possible to explicitly set the Tag when using StaticArrays to calculate an out-of-place Jacobian. This is needed when f uses preallocated internal buffer arrays, which must match the Dual number type. For other array types, this can be set by supplying a cfg::JacobianConfig, however this argument is ignored when using StaticArrays.
Looks like the problem is in jacobian.jl L85-87 which then calls L183-186 so any cfg argument to jacobian is ignored, and the Tag is always autogenerated.
Related:
Discussion in issue 296, https://github.com/JuliaDiff/ForwardDiff.jl/issues/296#issuecomment-365045955
PR https://github.com/JuliaDiff/ForwardDiff.jl/pull/304
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Research direction
Start in src/jacobian.jl at lines 85-87 and 183-186, where the issue reports that the supplied JacobianConfig is ignored for StaticArrays. Read issue 296 and PR 304 for prior context, then verify that an explicitly supplied Tag is honored for out-of-place StaticArray Jacobians, including the preallocated-buffer use case.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- julia
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Clearly specified
- Newbie friendliness
- 48/100