s not directly support masked arrays. To use it on a masked array, convert the mask into zero weights: >>> a = np.ma.array([np.log(2), 2, np.log(3)], ... mask=[False, True, False]) >>> b = (~a.mask).astype(int) >>> logsumexp(a.data, b=b), np.log(5) 1.6094379124341005, 1.6094379124341005 T)