Subscripted variables and function definitions
- To: mathgroup at smc.vnet.net
- Subject: [mg65192] Subscripted variables and function definitions
- From: Geico Caveman <spam at spam.invalid>
- Date: Fri, 17 Mar 2006 00:13:34 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hi I am trying to define a function (using the front end - I will be using latex syntax in this post to make clear what I am doing) : A[k_s_,r_t_,r_k_]:=... Now after this, if I try to output A[1,1,1], it just throws A[1,1,1] back. However, if I define : A[ks_,rt_,rk_]:=... it gives the right answer. Two questions : 1. Why aren't subscripted variable names treated the same as other variable names in this context ? 2. Is there a way to coax Mathematica into doing what I am trying to do above ? Mathematica is a nice system, but it has these highly irritating quirks. Another (unrelated) question : I have a 4x4 matrix which is a function of some variables : A:=... (function of r1,r2,r3, ...) f:=... (function of the same variables) X:=Inverse[A] . f Now, I want to extract a ratio : X/(X+X) and assign it to a function : g[r1_,r2_,r3_]:=X/(X+X) A test evaluation of g[1,1,1] throws g[1,1,1] back. Makes no sense at all to me. What am I missing, and why is Mathematica so unintuitive here ?