In linear algebra, the condition number plays a well-known role in quantifying the reliability of solutions. In the numerical solution of differential equations, the phenomenon of sensitivity to perturbations is often illustrated, but it is less common to see a condition number. In this post, I compare and contrast two approaches to quantifying stability. Examples include a dart throw (from a book by Fox and Mayers) and a devious hole of miniature golf.
Full text: The condition number for differential equations.