# 3: Numerical Methods

- Page ID
- 9410

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In this chapter we study numerical methods for solving a ﬁrst order differential equation \(y' = f(x,y) \nonumber\).

- 3.1: Euler’s Method
- This section deals with Euler’s method, which is really too crude to be of much use in practical applications. However, its simplicity allows for an introduction to the ideas required to understand the better methods discussed in the other two sections.

- 3.2: The Improved Euler Method and Related Methods
- Euler’s method implies that we can achieve arbitrarily accurate results with Euler’s method by simply choosing the step size sufficiently small. However, this isn’t a good idea, for two reasons. (1) After a certain point decreasing the step size will increase roundoff errors to the point where the accuracy will deteriorate rather than improve. (2)The expensive part of the computation is the evaluation of the solution. This section discusses improvements on Euler’s method.

- 3.3: The Runge-Kutta Method
- This section deals with the Runge-Kutta method, perhaps the most widely used method for numerical solution of differential equations.