Continuous Models

Abstract

In mathematics textbooks, variables usually take any real value (i.e. they ‘go from −∞ to +∞’). In modelling this is never so because:

• 1. Variables represent real quantities and have practical upper and lower limits, and in many cases negative values are physically meaningless.

• 2. Models have a limited domain of applicability, outside of which some of the assumptions break down and the model should not be used.