most recent 30 from http://mathoverflow.net 2013-06-19T08:35:59Z http://mathoverflow.net/feeds/user/27227 http://www.creativecommons.org/licenses/by-nc/2.5/rdf http://mathoverflow.net/questions/109578/about-the-gradient-field-of-the-distance-function unknown (yahoo) 2012-10-14T04:07:54Z 2012-10-14T04:07:54Z

<p>Suppose A be a point on a geodesically complete Riemannian manifold (M,g),and define a distance function on M, r(x)=d(x,A).One can see intuitively that the gradient vector of the distance function at x is just the targent vector at x of the geodesic connecting x and A, with length 1.</p> <p>My question is where can I find a formal proof ? </p>