Free public beta until December 4, 2026: every course is open, no card needed. After that, the first chapter of each course stays free and full access is a one-time $39 ($19 for up to 100 founding members chosen for helpful feedback). Your progress is kept. How the beta works

🎯

Orthogonal Projection Sprint

A Fourier coefficient is just an orthogonal-projection ratio -- divide the inner product by the basis function's own squared norm, $\pi$.

⏱️ 60s

▶ Log in to play

← Back to the arcade