# Introduction to Numerical Methods/Introduction

Mathematical models are a central piece of science and engineering. Some
models have closed-form solutions, therefore they can be solved
analytically. Many models can not be solved analytically or the analytic
solution is too costly to be practical. All models can be solved
computationally and the result may not be the exact answer but it can be
useful. George E. P. Box was right by saying All models are wrong, but
some are useful. Since
errors are inevitable a more practical question we ought to ask is how
close the answer needs to be for it to be useful. In lots of engineering
situations the only way to get the \"right answer\" is to use the
following formula:

right answer = wrong answer + corrections

Missile Knows Where It Is
is an audio click explaining how a missile guidance system can possibly
work by repeatedly correcting it errors.

Before we discuss how to manage errors lets explore the sources of
errors.

