only log chi2 once, not each loop
only log chi2 once, not each loop

allisony/pyspeckit,e-koch/pyspeckit,vlas-sokolov/pyspeckit,low-sky/pyspeckit,keflavich/pyspeckit,mikelum/pyspeckit,jpinedaf/pyspeckit,allisony/pyspeckit,bsipocz/pyspeckit,low-sky/pyspeckit,e-koch/pyspeckit,bsipocz/pyspeckit,pyspeckit/pyspeckit,mikelum/pyspeckit,keflavich/pyspeckit,pyspeckit/pyspeckit,vlas-sokolov/pyspeckit,jpinedaf/pyspeckit