Continuous distributions

Level UniversityDifficulty ★★★★★Concept⌖ Open in the map

What is it?

The workhorses: uniform (random number generators), exponential (waiting times, memoryless), normal (sums of many small effects, by the central limit theorem), and their multivariate versions.

Formulas

𝒰(a,b):1b−a,Exp⁡(λ):λe−λx,𝒩(μ,σ2):1σ2πe−(x−μ)2/2σ2\mathcal U(a,b): \tfrac{1}{b-a}, \qquad \operatorname{Exp}(\lambda): \lambda e^{-\lambda x}, \qquad \mathcal N(\mu,\sigma^2): \tfrac{1}{\sigma\sqrt{2\pi}}e^{-(x-\mu)^2/2\sigma^2}
XˉN−μσ/N→ d 𝒩(0,1)\frac{\bar X_N - \mu}{\sigma/\sqrt N} \xrightarrow{\ d\ } \mathcal N(0,1)
central limit theorem

Where it shows up in computing

  • Queueing theory and performance★★★★★fundamentalOptimization and systems

    Poisson arrivals have exponential inter-arrival times — the basis of M/M/1 models of servers.

  • Kalman filter★★★★★fundamentalRobotics and control

    Gaussian noise assumptions make the Kalman filter optimal and closed-form.

Where it shows up in AI

  • Generative models★★★★★frequentAI and machine learning

    Diffusion models add Gaussian noise; VAEs use Gaussian latent variables.

Where is it used?

Computing topics reachable from here, through the chain of ideas that leads to them:

This page has the essentials. A fuller treatment (intuition, formal definition, worked example) is on the way.

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