Q: implementation of Dot
- To: mathgroup at smc.vnet.net
- Subject: [mg7895] Q: implementation of Dot
- From: Andreas Unterkircher <unterkir at ifu.bepr.ethz.ch>
- Date: Thu, 17 Jul 1997 15:35:55 -0400
- Organization: ETH Zuerich
- Sender: owner-wri-mathgroup at wolfram.com
Hello !
I am puzzled about the following behaviour of the Mathematica (version
3.0) function "." (Dot):
In[1]= n = {{x},{y}};
In[2]= nn = {z};
In[3]= n . nn
Out[3]= {xz,yz}
Now I try
In[4]= m = {{},{}};
In[5]= mm = {};
In[6]= m . mm
Out[6]= {0}
I would have expected that either the operation m . mm (In[6]) is not
allowed at all or that Out[6] gives something like "{,}". I would
appreciate it very much if anybody can explain this behaviour to me.
Thanks,
Andreas
--
Andreas Unterkircher Institut fuer Umformtechnik
ETH Zentrum / CLA, Tannenstr. 3,CH-8092 Zuerich, Switzerland
Phone: ++43 1 632 6621 http://www.ifu.ethz.ch