Wavelet Toolbox

Complex Continuous Analysis Using the Command Line

This example involves a cusp signal.

Loading a Signal.   

1. From the MATLAB prompt, type:

   load cuspamax; 
   

You now have the signal cuspamax in your workspace:

whos

	Name	Size	Bytes	Class
	caption	1x71	142	char array
	cuspamax	1x1024	8192	double array

 
 

caption

caption =
       x = linspace(0,1,1024);
       y = exp(-128*((x-0.3).^2))-3*(abs(x-0.7).^0.4);

caption is a string that contains the signal definition.

Performing a Continuous Wavelet Transform.   

2. Use the cwt command. Type:

   c = cwt(cuspamax,1:2:64,'cgau4');
   

The arguments to cwt specify the signal to be analyzed, the scales of the analysis, and the wavelet to be used. The returned argument c contains the coefficients at various scales. In this case, c is a complex 32-by-1024 matrix, each row of which corresponds to a single scale.

Plotting the Coefficients.   

The cwt command accepts a fourth argument. This is a flag that, when present, causes cwt to produce four plots related to the complex continuous wavelet transform coefficients:

• Real and imaginary parts
• Modulus and angle.

The cwt command can accept more arguments to define the different characteristics of the produced plots. For more information, see the cwt reference page.

3. Type:

   c = cwt(cuspamax,1:2:64,'cgau4','plot');
   

A plot appears:

Of course, coefficient plots generated from the command line can be manipulated using ordinary MATLAB graphics commands.

One-Dimensional Complex Continuous Wavelet Analysis

Complex Continuous Analysis Using the Graphical Interface