Engineering Analysis/Distributions

From Wikibooks, open books for an open world
< Engineering Analysis
Jump to: navigation, search

Distributions[edit]

There are a number of common distributions, that are used in conjunction with random variables.

Uniform Distribution[edit]

The uniform distribution is one of the easiest distributions to analyze. Also, uniform distributions of random numbers are easy to generate on computers, so they are typically used in computer software.

f_X(x) = \left\{ \begin{matrix}\frac{1}{b - a} & \mbox{ if } a < x < b \\0 & \mbox{ otherwise}\end{matrix}\right.
F_X(x) = \left\{ \begin{matrix}0 & \mbox{ if } x < a \\ \frac{x}{b - a} & \mbox{ if } a < x < b \\1 & \mbox{ if } x \ge b\end{matrix}\right.

Gaussian Distribution[edit]

The gaussian distribution, or the "normal distribution" is one of the most common random distributions. A gaussian random variable is typically called a "normal" random variable.

f_X(x) = \mathcal{N}(\mu, \sigma^2) = \frac{1}{\sqrt{2 \pi \sigma^2}} e^{-\frac{(x - \mu)^2}{\sigma^2}}

Where μ is the mean of the function, and σ2 is the variance of the function. we will discuss both these terms later.

Exponential Distribution[edit]

Poisson Distribution[edit]