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36 lines
1.5 KiB
Markdown
36 lines
1.5 KiB
Markdown
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# [Choosing an assembly strategy](@id assembler_choice)
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JuliaFEM **0.x** exposes more than one assembly path. This page matches the
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split under `src/assemblers/` and the regression tests.
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## DOF-based COO (`DOFBasedCOOAssembler`)
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- **Use when:** you want the modern, matrix-free-friendly pipeline: one cache
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drives both sparse triplets and `apply_K!` / Krylov operators.
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- **Strengths:** walks global DOF rows with `local_dof_layout` decoding; the
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hot path is written for zero allocations after warmup
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(`test/assemblers/test_dof_based_zero_alloc.jl`).
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- **Tests:** `test/assemblers/test_dof_based_apply_K.jl` and related
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`test_dof_based_*.jl` files.
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## Element-based COO / CSC
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- **Use when:** you want the classical element-by-element scatter into COO or
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CSC as a reference implementation or for tooling that expects element loops.
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- **Strengths:** straightforward comparison to textbook element assembly.
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- **Code:** `src/assemblers/element_based/`; see `src/assemblers/README.md`.
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## Matrix-free operators
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- **Use when:** you do not want to form `K` explicitly (large systems,
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matrix-free Newton–Krylov).
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- **Strengths:** composable Dirichlet, MPC, loads, and preconditioners under
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`src/assemblers/matrix_free/`.
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- **Tests:** `test/assemblers/test_matrix_free_operator.jl` and neighbors.
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- **Site guide:** `juliafem.github.io/docs/user-guide/matrix_free_cookbook.md`.
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## Rule of thumb
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Start with **DOF-based COO** for new physics and examples unless you have a
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specific reason to call the element-based scatter directly.
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