MATLAB code that can replace the inbuilt function 'norm'

Hello, I need to substitute the inbuilt function 'norm' with other matlab code that execute the same function. This is because the function 'norm' is not permitted to be translated using the MATLAB HDL Coder function.

Thank you in advance for the help!

[amin ya]

There are many norm functions in MATLAB, which one do you mean?

Have you looked here:

https://www.mathworks.com/matlabcentral/fileexchange?q=norm

[Yue Han Seow]

I'm not really sure which type of norm it is,

w1 = norm(win,1)

this is the equation that uses the norm function

[madhan ravi]

Have you seen?:

https://in.mathworks.com/help/matlab/ref/norm.html#bt0y64b-1-p

https://in.mathworks.com/help/symbolic/norm.html?searchHighlight=norm&s_tid=doc_srchtitle#btke0hr-37

[John D'Errico]

As importantly, what is win? Is win a vector? Is win a matrix?

[Yue Han Seow]

win is a window

Answer 1

[John D'Errico]

I suppose I can write a simple 1-norm code, that will work for a vector OR matrix.

Thus, the 1-norm of a vector is the sum of absolute values of the vector. So, if X is a vector, then norm(X,1) == sum(abs(X)).

If X is a matrix? Then the 1-norm is the maximum sum of all columns of the matrix. We can see how this works:

X = rand(3,3)
X =
      0.72105      0.21868     0.063591
       0.5225       0.1058      0.40458
       0.9937       0.1097      0.44837
>> norm(X)
ans =
       1.4581
>> max(sum(abs(X),1))
ans =
       2.2372
>> norm(X,1)
ans =
       2.2372

So now we can write a code that will work for any vector or matrix, computing the 1-norm.

function res = norm1(X)
if isvector(X)
   res = sum(abs(X));
else
   res = max(sum(abs(X),1));
end

This code does not replace norm, in the sense that it is far simpler. It does not compute a 2-norm, or any other norm. It does not work for 3-d matrices, but then, neither does norm work there.

[Yue Han Seow]

Thank you so much for your explanation and example! It helps me to understand it better!