In this chapter we describe more of MATLAB's graphics commands and the most common ways of manipulating and customizing them. You can get a list of MATLAB graphics commands by typing help graphics (for general graphics commands), help graph2d (for two-dimensional graphing), help graph3d (for three-dimensional graphing), or help specgraph (for specialized graphing commands).

We have already discussed the commands plot and ezplot in Chapter 2. We will begin this chapter by discussing more uses of these commands, as well as the other most commonly used plotting commands in two and three dimensions. Then we will discuss some techniques for customizing and manipulating graphics.

Two-Dimensional Plots

Often one wants to draw a curve in the x-y plane, but with y not given explicitly as a function of x. There are two main techniques for plotting such curves: parametric plotting and contour or implicit plotting. We discuss these in turn in the next two subsections.

Parametric Plots

Sometimes x and y are both given as functions of some parameter. For example, the circle of radius 1 centered at (0,0) can be expressed in parametric form as x = cos(2πt), y = sin(2πt) where t runs from 0 to 1. Though y is not expressed as a function of x, you can easily graph this curve with plot, as follows:

The output is shown in Figure 5.1.