Variance of a histogram in matlab
Your distribution is bi-modal and not Gaussian. I'm assuming you want to find the variance of each of the two modes (which look Gaussian by themselves).

In your case the modes don't seem to overlap, so the easiest way would to split this into positive and negative values

q1 = q(q &gt; 0);
q2 = q(q &lt; 0);
v1 = var(q1);
v2 = var(q2);