function feat = norm_var(feat, std_parm)

M = size(feat,1);

if(nargin == 1)
    std_parm = ones(M, 1);
end

% input should be of size Dimension * Observations.

vp = sqrt(mean(feat .* feat, 2));
vp = vp./std_parm;

feat = feat./repmat(vp, 1, size(feat,2));