docs: def from_semiaxes(cls,axes):
          """
          Get axis-aligned elliptical conic from axis lenths
          This can be converted into a hyperbola by getting the dual conic
          """
          ax = list(1/N.array(axes)**2)
          #ax[-1] *= -1  # Not sure what is going on here...
          arr = N.diag(ax + [-1])
          return arr.view(cls)