Commits on 9 Oct 2026
Beam: strike and listening at positions along the beam (m), hammer blow of fixed physical width, so both mean the same at any N; N = 8 unchanged
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8ce184cAnti-alias filter for rendered notes (beam, fput-chain): 4x oversampling, Kaiser FIR low-pass to 0.42 fs, decimation; beam warning now says modes above the passband are filtered out
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0172972Beam: integrator step 0.2 / omega_eff (was 0.03): 6.5x fewer steps, top-mode pitch error 2.9 cents, statistically equivalent notes
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1115407Beam: Masses refines the same beam (parameters for 8 masses, scaled with the spacing), so the low modes, decay times and note length stay put as N grows
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fcad6beBeam: frequency-dependent loss (dashpots alongside the springs, set by the top-of-band decay time τ top, default off); per-mode decay times in the derived values
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462e79cBeam README: 1:2 internal resonance between modes 1 and 3 (Kirchhoff, clamped, h = 0.38)
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e39a676Beam README: the near 2:1 at h = 0.2 is not a resonance (mode 2 antisymmetric)
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2079531Beam: draw the rest shape and the beam at rest shape plus displacement
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82fcd7fBeam: curvature (rise h of a stress-free curved rest shape, default 0); stepFor safe for k3 = 0
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551b7a9Chart legends fit left of the range text; the rest counted as +n
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64125ddSpectrogram: log frequency axis by default with a 'log f' chip for linear; rows show the loudest bin in their band; mode lines decided per line
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63e5e6eBeam step 5: λ vs E scatter over notes
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90c1386Beam step 4: ghost and Separation chart; ghost controls shared in src/common/ghost.ts, used by all three apps
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8776c93Beam step 3: mode bars, mode history, mode energies, note's mode heat map; mode history and mode bars shared in src/common/
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407a5c8Beam step 2: Lyapunov exponent (real-time chart, note chart with energy); render loop shared in src/common/note-render.ts, used by fput-chain (output unchanged)
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f8def18Beam app (step 1): beam with bending, clamped/pinned/cantilever ends, local or Kirchhoff stretching; sped-up note with spectrogram. Note player, mute button, formats and canvas sizing in src/common/
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8cbfe83Section panel in src/common/section-panel.ts; each app configures it. Pendulum section slider on a log scale (E_top/1000 to 2 E_top)
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8874f6dSection orbits, worker and atlas in src/common/; each app supplies sectionOf(P)
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d063b02Lyapunov method in src/common/lyapunov.ts; each app supplies its Shadow
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50e44e5Shared styles in src/common/style.css; each app's own rules in its style.css, imported after
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420fab0Move spectrogram and traces to src/common/ (fput's versions, a superset of the pendulum's)
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5962540Move the identical files (help, cursor, wav, scatter) to src/common/
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5ae1944One multi-page Vite site: shared config at the root, landing page, apps at /double-pendulum/ and /fput-chain/
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d1459b9Merge fput-chain history (from fput-chain-chaos)
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988367fRemove bending stiffness κ (moving to a separate app); keep note Lyapunov shadow only when shown
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49ec7e1Bending stiffness κ (pinned ends) as a parameter; aliasing warning; note Lyapunov shadow only when shown; settings to try
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3aefce3Pitch down to 5 Hz with a longer spectrogram window at low pitch; Modes chip off by default
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55cfe71Commits on 8 Oct 2026
Help buttons on each card and panel
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cb30402Poincaré section for N = 2 and N = 3's symmetric family, with Follow (real time, sped up) and precomputed sections; default N = 2
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1a6659dREADME: live site link
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7a040c1FPUT chain chaos: struck FPUT-beta chain with damping, real-time plots, ghost, Lyapunov, and a sped-up listen panel
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52a89c0Rename to double-pendulum-chaos
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