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Technical Guide Overview

Brian S. Yandell

03 August 2026

index.Rmd

The Technical Guide serves as the comprehensive internal technical reference manual for the ewing package. While the high-level Developer Guide covers Shiny module composition and dashboard architecture, this guide details the deep mathematical foundations, state engine physics, spatial geometry, thermal spline integration, and GIS watershed overlay algorithms governing the package.

Technical Domain Sections

  • I. Simulation Engine: Explains the central community simulation state object, organism feature matrices, leftist-tree event queue scheduling, competing risk stage transitions, and operational execution loops.
  • II. Substrate Geometry: Technical specification of the tridiagonal coordinate system (a,b,c)(a, b, c), plant substrate topology (substrate_topology), unit coordinate rescaling ([0,Wsub][0, W_{sub}]), 6-sided hexagonal polygon tile overlays (create_hex_overlay), and substrateApp module architecture.
  • III. Thermal Regimes: Interactive temperature-time spline design (temp.design, tempApp), degree-day integration (activeTemp), 5-parameter mean value sensitivity (fivePlotApp, fiveShowApp), and Shinylive WebAssembly demos.
  • IV. GIS Watersheds: Interactive geographic feature search and watershed discovery utilities (leafletApp, hexmapApp), spatial projection of simulation grids onto USGS HUC12 subwatershed boundaries (watershed_overlay), and Shinylive WASM / Posit Connect deployment.
  • V. UI Architecture: Architecture for upgrading the Systems Ethology continuous interactive graphical interface (sysetholApp, ewingApp), sidebar de-cluttering with conditionalPanel, multi-species hex overlay layouts, downloadApp integration, and engineering prompt history.