I'm wondering if it's possible to calculate in a percentage how symmetric a matrix is. So f.e. even if a matrix is not symmetrical, instead of just classifying it as "not symmetric" say that it's "symmetric with 80%". 

My overall goal is to get kind of a "symmetry value" adding up values from different kind of symmetry like translational, rotational, etc. 

I appreciate any help :)

Thanks!