6 hours ago
- Spreadsheet recalculation evolved from VisiCalc's inefficient left-to-right, top-to-bottom method to Lotus 1-2-3's natural-order recalculation, which recalculates all cells once.
- SuperCalc5 improved efficiency by recalculating only cells dependent on changed inputs, reducing unnecessary computation but risking incorrect order of recalculation.
- Two main solutions for correct recalculation order are dirty marking (marking downstream cells as dirty) and topological sorting (using heights to prioritize cells), each with trade-offs in performance.
- Modern Excel combines dirty marking and topological sorting, while demand-driven computation like Salsa or Adapton focuses on recalculating only observed cells to save time.
- Adapton and Incremental optimize for different scenarios; Anchors hybridizes both by running them simultaneously, switching strategies based on cell observation changes.