How to replace some variables and how to solve a differential equation?
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- Subject: [mg132359] How to replace some variables and how to solve a differential equation?
- From: bluesaturn <bluesaturn.at.kellnerweg.de at gmail.com>
- Date: Thu, 20 Feb 2014 03:27:39 -0500 (EST)
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Dear all, I am really new to Mathematica. I have two questions, please. 1. How to replace a variable in a function? I have defined: f[r_] := Log[((2*\[Lambda])/(\[Kappa]*r* Cos[\[Lambda]*Log[(r/RM)]]))^2] RM, lambda >0 I want to replace r with u given by u=log[Kappa*r] I did it by hand but whant to check my result. 2. How to check or solve the differential equation: f"[u]=0.5*exp[2*u+f[u]] It would be sufficient for me to insert f[u] and see if both sides are the same. So far I failed. Thank you for your help. Regards Blue