       Re: using predefined expressions in functions [newbie

• To: mathgroup at smc.vnet.net
• Subject: [mg100211] Re: [mg100167] using predefined expressions in functions [newbie
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 28 May 2009 04:28:50 -0400 (EDT)

```R1 := {x1, y1, z1}
R2 := {x2, y2, z2}

Don' t use SetDelayed in definition of f

f[x1_, y1_, z1_, x2_, y2_, z2_] = R1.R2;

f[1, 2, 3, 4, 5, 6]

32

Bob Hanlon

---- ChangMo <nichthierwohne at gmail.com> wrote:

=============
Hi,

I've been trying to write a function using some predefined
expressions, but the function assignment seems to understand the
symbols in the expressions as literals. eg.,

Needs["VectorAnalysis`"]
R1 := {x1,y1,z1}
R2 := {x2,y2,z2}
f[x1_,y1_,z1_,x2_,y2_,z2_] := R1 . R2

f[1,2,3,4,5,6]

gives the output
x1 x2 + y1 y2 + z1 z2
32 ( = 1*4 + 2*5 + 3*6 )

Can anyone help me with this?  Thanks for your attention.

-ChangMo

```

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