  for the square of the length \(ds\) of an infinitesimal line  element that leads from the point \(p = x(p) =  (x^{1}(p), \ldots ,x^{n}(p))\) to an arbitrary infinitely  near point \(p' = x(p') = (x^{1}(p) + dx^{1}(p), \ldots ,x^{n}(p) + dx^{n}(p))\). 