AW: "a[A_,B_] :=" Does not assign variables properly. Why?
- To: mathgroup at smc.vnet.net
- Subject: [mg36149] AW: [mg36141] "a[A_,B_] :=" Does not assign variables properly. Why?
- From: Matthias.Bode at oppenheim.de
- Date: Fri, 23 Aug 2002 21:34:38 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello,
try
In[1]:=Clear[a,b,c,d,x,y]
x= {{0,0,0,1},{1,0,0,1},{0,1,0,1},{1,1,1,1}};
y = {a,b,c,d};
LinearSolve[x,y]
s01= LinearSolve[x,y][[1]]
Out[4]={-a+b,-a+c,a-b-c+d,a}
Out[5]=-a+b
In[6]:=g[a_,b_] =s01
Out[6]=-a+b
In[7]:=g[1,3]
Out[7]=2
*NEVER* use capital letters at the beginning of a variable's name! Never!
Best regards,
Matthias Bode
Sal. Oppenheim jr. & Cie. KGaA
Koenigsberger Strasse 29
D-60487 Frankfurt am Main
GERMANY
Tel.: +49(0)69 71 34 53 80
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-----Ursprüngliche Nachricht-----
Von: jwelter at sawtek.com [mailto:jwelter at sawtek.com]
Gesendet: Freitag, 23. August 2002 06:25
An: mathgroup at smc.vnet.net
Betreff: [mg36141] "a[A_,B_] :=" Does not assign variables properly.
Why?
Here's a piece of a conversion I had with Mathematica.
Why is "a[A_,B_] := LinearSolve[X,Y][[1]]" not giving
me the function I expect?
In[261]:= X = {{0,0,0,1},{1,0,0,1},{0,1,0,1},{1,1,1,1}};
In[262]:= Y = {A,B,C,D};
In[263]:= LinearSolve[X,Y]
Out[263]= {-A+B,-A+C,A-B-C+D,A}
In[264]:= LinearSolve[X,Y][[1]]
Out[264]= -A+B
In[265]:= a[A_,B_] := LinearSolve[X,Y][[1]]
In[266]:= a[1,3]
Out[266]= -A+B
The output above is not what I want. I want "2". Here's
what I expect:
In[267]:= a[A_,B_] := -A+B;
In[268]:= a[1,3]
Out[268]= 2
This output is what I expect. What is the difference between
the two?