- Implement COOAssembler using coordinate (triplet) format
- Implement create_cache() for COOCache creation
- Implement assemble!() with zero-allocation element traversal
- Implement scatter_to_triplets!() for in-place triplet accumulation
- Implement scatter_to_force!() for force vector assembly
- 247 lines of COO assembly implementation
Algorithm:
1. Loop over elements
2. Compute element stiffness using kernel (in-place)
3. Get DOF mapping (in-place)
4. Scatter Ke to triplet arrays (I, J, V)
5. Scatter fe to global force vector
6. Build sparse matrix at end: sparse(I, J, V)
Performance characteristics:
- Baseline reference implementation (1.0x)
- Simple and robust
- Moderate memory usage
- Best for prototyping and debugging
Zero-allocation assembly:
- All arrays pre-allocated in cache
- Element cache reused for all elements
- No heap allocations during assembly loop
Jukka Aho