feature selection: Signal to noise score and kruskal-willis for gene expression data

Hi, I am a new user for this software, and I am interested in making a feature selection of my gene expression data using signal to noise ratio and kruskall-willis. But the thing is, the formulaI got from the paper reference doesn't help a lot and I have big difficulties in converting the formula on paper to matlab code. here is my gene expression data

Can anyone help me with this?