Four classic results from real analysis appear here side by side.
The Gaussian ∫₋∞⁺∞ e⁻ˣ² dx = √π
The arctangent ∫₋∞⁺∞ 1/(x²+1) dx = π
Dirichlet’s ∫₋∞⁺∞ (sin x)/x dx = π
And ∫₋∞⁺∞ cos(x)/(1+x²) dx = π/e
Digital audio codecs rely on the sinc integral to enforce the Nyquist rate that prevents aliasing in compressed music files.