Biology
Action Potential (Hodgkin–Huxley)
C dV/dt = I − gNa·m³h(V−ENa) − gK·n⁴(V−EK) − gL(V−EL)

A steady stimulus current drives a repetitive train of nerve spikes as fast Na⁺ influx and slower K⁺ efflux chase each other, integrated live with the library's Hodgkin–Huxley RK4 solver.
Computed & rendered in pure C# on the frozen OnlyCSharp 1.8 library — animation baked to GIF with the library's own
Gif encoder (no GPU, no ffmpeg, no external packages).