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Variable transformations

  • To: mathgroup at smc.vnet.net
  • Subject: [mg131437] Variable transformations
  • From: Nicholas Chisholm <nick.g.chisholm at gmail.com>
  • Date: Tue, 23 Jul 2013 04:44:42 -0400 (EDT)
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Say I have some differential equation in terms of the independent variable x and dependent variable f(x). Now say I want to do a coordinate/variable transformation where x=x(u) and I want to write my equation in terms of only u and f(u). By pencil & paper, you can do this by applying the chain rule, but I have a complicated equation and I want to check if I've made an algebra slip-up (it involves several dependent and independent variables and up to 4th order derivatives). Is there any way to automate something like this in Mathematica? I've messed around with replacement rules, but I can't get Mathematica to do things quite how I want.

Thanks!



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