How to do whitening on the given matrix?

 X = rand(100,20); % 100 instance with 20 features
 N= size(X,2);
 M=size(X,1);
 meanX=mean(X,2);
 Xm=X-meanX*ones(1,N);
 C= ( Xm*Xm')/N;
 [U D]=eig(C);

How to whiten this above matrix??

[Image Analyst]

Perhaps this: https://www.mathworks.com/matlabcentral/fileexchange/34471-data-matrix-whitening?s_tid=answers_rc2-2_p5_MLT

http://www.mathworks.com/matlabcentral/answers/13205#answer_18099

[Darsana P M]

How will i do it without using function?

Answer 1

[Kenta]

ZCA whitening is avaliable here.

https://jp.mathworks.com/matlabcentral/fileexchange/74990-zca-whitening-for-image-classification-zca