- #1
RedX
- 970
- 3
What is the relationship between being globally diffeomorphic and the Jacobian of the diffeomorphism?
All I can think of is that if the Jacobian at a point is non-zero, then the map is bijective around that point. For example, if:
[tex]f(x)=x_0+J(x_0)(x-x_0)[/tex]
where J(x0) is the Jacobian matrix at the point x0, x is the coordinate on one manifold, f(x) is the mapped coordinate to the other manifold, then this can easily be inverted for a non-zero Jacobian:
[tex]J^{-1}(x_0)[f(x)-x_0]+x_0=x[/tex]
So it seems that having a non-vanishing Jacobian only proves that f is a bijection and that f is C1, but does not prove that f is infinitely differentiable.
All I can think of is that if the Jacobian at a point is non-zero, then the map is bijective around that point. For example, if:
[tex]f(x)=x_0+J(x_0)(x-x_0)[/tex]
where J(x0) is the Jacobian matrix at the point x0, x is the coordinate on one manifold, f(x) is the mapped coordinate to the other manifold, then this can easily be inverted for a non-zero Jacobian:
[tex]J^{-1}(x_0)[f(x)-x_0]+x_0=x[/tex]
So it seems that having a non-vanishing Jacobian only proves that f is a bijection and that f is C1, but does not prove that f is infinitely differentiable.