how to check if my data has unit scale(mean=0,variance =1)

I have to apply princomp(Matlab) to a feature matrix.But have few queris: 1.How do I check if the feature matrix has unit scale((mean=0,variance =1)? 2.If it has unit scale can I use it directly as raw input to princomp or still do I have to use zscore to standardize it?

Answer 1

[Von Duesenberg]

I may be missing something, but it sounds like your answer is contained within your question. If you want to check that your features have zero mean and unit variance, you just have to compute the mean and the variance (with the functions mean and var); and if you find out that they do have zero mean and unit variance, then applying a z-score will have no effect.

[Radhika Bhagwat]

@Von, thanks for the reply. I too actually thought of finding the mean and variance of the feature matrix after posting the question.I found that the mean is 0.0060 and variance is not 1(starts with 0.0199 for 1st col decreasing upto 1.9423e-006). So will be applying zscore to the feature matrix. Thanks again for the reply. It confirmed what I was thinking.