Online Resource 1 for the manuscript "Long-Wave Instability in Confined Pedestrian Flow: A Reduced Dynamical-Systems Framework" submitted to International Journal of Dynamics and Control.

Article title: Long-Wave Instability in Confined Pedestrian Flow: A Reduced Dynamical-Systems Framework
Journal name: International Journal of Dynamics and Control

All quantities are nondimensional illustrative values, not event-specific measurements.
Software requirements: Python 3.9 or later, NumPy and matplotlib.
Run command: python stability_calculations.py
Outputs are written to a reproduced_outputs/ directory beside the script.
Fig. 2 uses tau=0.85. Fig. 3 varies tau from 0.2 to 2.5. Fig. 4 uses tau=1.05 and rho0/rho_jam=0.82.
No hidden wave-number scaling, growth truncation, or field clipping is applied in Fig. 4; wave_number_scaling=1.0, growth_truncation=none, and field_clipping=none are recorded in figure4_modes.csv.
