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May 27, 2015 at 10:19 answer added John B timeline score: 2
Feb 13, 2015 at 0:52 comment added Pietro Majer Given $F$ and $\Psi$, the transformation $M$ that makes (2) true may be found solving the last condition you wrote for $M(y)$, at least if $F(y)$ is injective.
Feb 13, 2015 at 0:37 comment added Pietro Majer I understand that (2) is a particular phenomenon arising in a special case Jorge is dealing with.
Sep 21, 2013 at 1:18 comment added Shuchang How do you obtain (2) from (1)? I don't see why there's (2)
Mar 28, 2013 at 13:56 answer added Issa timeline score: 0
Dec 19, 2011 at 16:36 history edited Jorge CC BY-SA 3.0
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Dec 19, 2011 at 16:04 comment added Jorge Ok let me just be a little more formal on the math. The vectors x,y∈Rn (column vectors), thus differentiating gives $\dot x=DΨ \dot y$ ($D\Psi \in \mathbb{R}^{n\times n}$- a square matrix). It is indeed the change of variables formula for the derivative.
Dec 19, 2011 at 13:49 comment added Jacques Carette Ok, I forgot that notation, I guess. Chain rule gives me $\dot{x} = \dot{y} \cdot D\Psi y$ for $x=\Psi y$. So there is a $y$ embedded in your $D\Psi$ which you elide (and some explicit computation confirm) that threw me off. Then the formula reads just like the change of variables formula on manifolds, no?
Dec 19, 2011 at 12:43 history edited Jorge CC BY-SA 3.0
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Dec 18, 2011 at 18:12 history edited Jorge CC BY-SA 3.0
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Dec 18, 2011 at 17:32 comment added Jorge Jacque, if you're referring to $\dot x=D\Psi \dot y$, then this is correct. You can calculate it using basic analysis.
Dec 18, 2011 at 14:15 comment added Jacques Carette Are you sure your elaboration is correct? In particular, it seems to me that in your very first line of your elaboration, you have not applied the chain rule properly. If you 'fix' that, you'll get a condition which is much more reasonable.
Dec 18, 2011 at 2:56 history edited Jorge CC BY-SA 3.0
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Dec 18, 2011 at 2:44 history asked Jorge CC BY-SA 3.0