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# MATLAB

## 2-D Plots

This example shows some of the many types of 2-D line that you can create with MATLAB and provides a few general plotting tips.

Line Plot of a Chirp

This example shows a basic line plot of a chirp signal. It also shows how to enter labels for the x and y axes using xlabel and ylabel as well as one method of initializing x-values. Type doc linspace at the command prompt for information on another method for initializing evenly spaced data sets. Here y-values are computed as a function of x and stored in the variable y, but you could also plot just the computed y-values in one command, for example, plot(sin((0:0.05:5).^2)).

x = 0:0.05:5;
y = sin(x.^2);
plot(x,y);
xlabel('Time')
ylabel('Amplitude')

Bar Plot of a Bell Shaped Curve

As just suggested, you don't need a variable to hold y-values if you pass a function that generates them to plot as its y-argument.

x = -2.9:0.2:2.9;
bar(x,exp(-x.*x));

Stairstep Plot of a Sine Wave

x = 0:0.25:10;
stairs(x,sin(x));

Errorbar Plot

The errorbar function draws a line plot of x and y values and superimposes on each observation a vertical error bar, the extent of which depends on an additional argument. Here the error data is created in line 3 using the rand function, which generates a sequence of random numbers.

x = -2:0.1:2;
y = erf(x);
e = rand(size(x))/10;
errorbar(x,y,e);

Polar Plot

This example plots the polar coordinates of the angle theta (t, in radians) versus the radius, rho.

t = 0:0.01:2*pi;
polar(t,abs(sin(2*t).*cos(2*t)));

Stem Plot

A stem plot draws a marker for each x, y value which is connected to a common baseline by a vertical line.

x = 0:0.1:4;
y = sin(x.^2).*exp(-x);
stem(x,y)

Scatter Plot

This example shows the relationship between traffic counts on two streets hour by hour using red stars for markers. The previous example used the default markers of empty blue circles. For more information on changing line styles, colors, and markers, type doc line, doc scatter, or doc line_props in the command line.