Re: Dimensions and Variables II

• To: mathgroup at smc.vnet.net
• Subject: [mg13720] Re: [mg13688] Dimensions and Variables II
• From: Wouter Meeussen <eu000949 at pophost.eunet.be>
• Date: Wed, 19 Aug 1998 01:38:13 -0400
• Sender: owner-wri-mathgroup at wolfram.com

```hi,

you will have to choose if you want to have intermediate forms in
'operator' notation (like Out[8] and Out[9]) or not.

It would also be a good time to study the difference between immediate
assignment (" = ") and delayed assignment (" := ").
Look also at the logical flaw in your reasoning when you write
>
>a[x_,y_,z_]:=f+g+h
>
arguments to functions are in fact 'dummy variables' that stand for any
given input. Only in the context "f takes the first argument, g the second
and h the last" would this eventually make sense. You force this behaviour
by saying 'In[6]'.

In[1]:= f[x_] := u x
g[y_] := v y
h[z_] := w z
In[4]:= a = f + g + h
b = f g h
Out[4]=f+g+h
Out[5]=f g h

In[6]:= a3[x_, y_, z_] = f[x] + g[y] + h[z]
b3[x_, y_, z_] = f[x] g[y] h[z] Out[6]=u x+v y+w z
Out[7]=u v w x y z

In[8]:=a[t1]
Out[8]=(f+g+h)[t1]

In[9]:=b[t1]
Out[9]=(f g h)[t1]
In[10]:=Through[a[t1]]
Out[10]=t1 u+t1 v+t1 w
In[11]:=Through[b[t2]]
Out[11]=(t2^3 u v w)
In[12]:=L[x_, y_, z_] := a[x, y, z] + b[x, y, z] In[13]:=L[g1, g2, g3]
Out[13]=(f g h)[g1,g2,g3]+(f+g+h)[g1,g2,g3] In[14]:=Through /@ %
Out[14]=f[g1,g2,g3]+g[g1,g2,g3]+h[g1,g2,g3]+f[g1,g2,g3] g[g1,g2,g3]
h[g1,g2,g3] In[15]:=L3[x_, y_, z_] := a3[x, y, z] + b3[x, y, z]
In[16]:=L3[g1, g2, g3]
Out[16]=g1 u+g2 v+g3 w+g1 g2 g3 u v w

I hope I didn't mud the waters to much.

wouter.

At 04:39 15-08-98 -0400, naum at condor.physics.ucsb.edu wrote:
>	I am starting to work on the variable problem.  I am woried that I
>wasn't clear enoughf in my news posting.  Here is simple version of the
>sort of  thing that I am doing.
>
>f[x_]:=2x
>g[y_]:=3y
>h[z_]:=4z
>
>a[x_,y_,z_]:=f+g+h
>b[x_,y_,z_]:=f*g*h
>
>L[x_,y_,z_]:=a+b
>
>Is there an easier way to do al this, like could I make V:={x,y,z} a
>list and  then just say L[V_]?  does every leval need the explit
>dependence declaration?   I have tried alot of things and none of then
>seem to work.
>		-NAUM
>
>
Dr. Wouter L. J. MEEUSSEN
w.meeussen.vdmcc at vandemoortele.be
eu000949 at pophost.eunet.be

```

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