How to solve this error?

What does num1 and num2 represents?

And it also has an error :

Undefined function or variable 'normal'.

Error in Coding (line 4)
[C,L] = wavedec(normal(:,num1)',5,'db1');

This is our code:

load('x.dat') 

num1=2;

num2=30;

[C,L] = wavedec(normal(:,num1)',5,'db1');

[madhan ravi]

What’s normal?

Answer 1

[Walter Roberson]

In the context of that code, normal should be the name of a variable containing multiple signals as channels, and normal(:,num1) should be extracting channel #num1 from the signal.

normal is not being used as a function name here, and there is nothing special about its name as a variable.

It might be used in a context where you were comparing signals between "normal" (healthy) and "abnormal" (diseased) -- but it is just a variable name.

[Chee Wan Ting]

Thank you!! I have a better understanding now