Updated 6 October 2026

Changelog

Chronology of ODEPLOT changes: UI, numerical modules, localization. Technical notes, no marketing copy. Newest first.

20 October 2026

  • New “Numerical methods” page: Euler / Heun (RK2) / RK4 reference — description, JSDoc-style pseudocode, step tables on one shared example y′ = y.
  • Table of contents with anchors; footer link above the copyright on every page; SEO and locales.
  • Interactive comparison on [−2; 2]: click-to-start, h slider, zoom and fit, cursor coordinates, pick a point on a curve; error vs eˣ as bands, stems and max|ε|.

16 October 2026

  • First-order ODE: compare Euler, Heun (RK2) and RK4 on one click; fixed curve colors (red / blue / green).
  • Step-size h slider in the Parameters island (island stays available without formula variables): large h makes Euler blow up while RK4 keeps shape.
  • Calculation-step table under the canvas (x, y, k₁…k₄) with CSV export; button styled like the screenshot control.
  • Coming in later updates: the same methods on 2D/3D systems and higher-order ODE pages.

6 October 2026

  • Formula parameters (a, b, …) moved from the panel under the formula to the Parameters island on the canvas, “Variables” section. On first-order and higher-order ODEs the island appears when parameters are present and hides when there are none. All six modules.
  • Each variable has a slider, an animation (oscillation between the lower and upper bounds), editable range bounds and speed 0.5×–4×. Animations run independently.
  • “Animate all in sequence” button: each parameter completes one full cycle and returns to its initial value before the next one starts.
  • When a parameter changes, existing curves are recomputed from their initial points instead of being cleared (first-order and higher-order ODEs, 2D and 3D systems).

29 September 2026

  • Fullscreen workspace (icon next to PNG): the canvas fills the screen; controls overlay it in the same corners. Exit via the same icon or Escape. All six modules.
  • Animation: menu on the play button (point count; endless spawn).
  • Spawn modes: impulse (next batch after the previous one finishes), cascade (a full batch, then another on the same curves; interval and 2–10 overlapping waves), linear (one point at a time).
  • Cascade: short tails; waves nearer the start of a trajectory are brighter, later waves fade.
  • 2D: cursor coordinates to hundredths; display can be toggled.
  • Changelog page; footer link on every section.

19 September 2026

  • ODEPLOT brand; UI languages EN, FR, KO, JA, ES, RU, BY (dropdown; first visit follows the browser language, crawlers are not redirected).
  • PNG and Share at the top-right of the canvas; palette, brush, animation and zoom under the plot; the Parameters island stays on the field.
  • KaTeX in the PDE “How it works” box and the variations “The idea” box.
  • Favicon set; Open Graph 1200×630 snapshot mode (Ctrl/Cmd+S).

17 September 2026

  • Six modules: first-order ODEs (direction field), order ≥ 2, 2D and 3D systems (Three.js), first-order PDEs (characteristics), calculus of variations (Euler–Lagrange).
  • RK4 integrator, presets, formula history, light/dark theme, Vite MPA and Tailwind CSS 4.3.