Symbols in expression

*To*: mathgroup at smc.vnet.net*Subject*: [mg89079] Symbols in expression*From*: sigmundv at gmail.com*Date*: Sun, 25 May 2008 03:22:00 -0400 (EDT)

Dear all, Define, say, r = {Cos[u] Sin[v],Sin[u] Sin[v],Cos[v]}. How can I write a function, which takes r as an argument and returns a list {u,v}? If we defined r[u_,v_]:=... it could be achieved fairly easily using DownValues. But how can I achieve it in this case? Kind regards, Sigmund Vestergaard

**Follow-Ups**:**Re: Symbols in expression***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>