Page 86 - A Guide to MATLAB for Beginners and Experienced Users

Chapter 5

MATLAB Graphics

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 special-
ized 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 dimen-
sions. 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.

ParametricPlots
Sometimes x and y are bothgiven 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 graphthis curve with plot, as follows:

>> T = 0:0.01:1;

67