find most variable genes on microarray dataset

Hi All, I have a 203*12600 where 12600 gene and 203 sample microarray dataset. And,I made some preporessing steps on microarray dataset. treshold, filtering and Log 10 transform. Then now, I want to find most variable genes (which have high variance) and select first 500 genes. How can I do this ? Can anyone help.

Answer 1

[Walter Roberson]

gvar = var(YourArray);
[most_var, varidx] = sort(gvar, 'descending');
var500idx = varidx(1:500);
var500samples = YourArray(:,var500idx);