Hi Josef, Indeed, for some applications one would like to have different units for different parts of an array. And that means that, at present, the quantity implementations that we have are no good at storing, say, a covariance matrix involving parameters with different units, where thus each element of the covariance matrix has a different unit. I fear at present it would have to be an object array instead; other cases may be a bit easier to solve, by, e.g., allowing structured arrays with similarly structured units. I do note that actually doing it would clarify, e.g., what the axes in Vandermonde (spelling?) matrices mean. That said, there is truly an enormous benefit for checking units on "regular" operations. Spacecraft have missed Mars because people didn't do it properly... All the best, Marten p.s. The scipy functions should indeed be included in the ufuncs covered; there is a fairly long-standing issue for that in astropy...