3-D distribution

Sometimes we would like to know the distribution of some objects in the space. The MATLAB function plot3 can display a three-dimensional plot of a set of data points of the (x, y, z) coordinates.

Here's an example of a helix:

t = 0 : pi/50 : 10*pi;
x = sin(t);
y = cos(t);
z = t;

Then the shape of this helix is

plot3(x, y, z)

Note that you can use the same line specification syntax of plot in plot3:

plot3(x, y, z, 'ro')

To help you read the 3-D plot, type

grid on

so you can have a feeling about the 3-D space. Also, you can type

axis equal

so that the x-, y-, and z-axis have the same scale, which gives you a better idea on how the distribution actually looks like. Or, you can type

axis square

to keep the x-, y-, and z-axis the same length.

More importantly, in the Figure Window, find and click on this icon: , then you can rotate your 3-D plot to any angle of view you like.