Re: equaltity of lists
- To: mathgroup at smc.vnet.net
- Subject: [mg19193] Re: equaltity of lists
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Tue, 10 Aug 1999 02:52:50 -0400
- References: <7o5ih1$rml@smc.vnet.net> <7ofaab$pnq$9@dragonfly.wolfram.com>
- Sender: owner-wri-mathgroup at wolfram.com
F. Mittermayr <mitterma at linz.vai.co.at> wrote in message news:7ofaab$pnq$9 at dragonfly.wolfram.com... > Why do I get the answer True when I ask Mathematica > > a=x; b=x^2/x; > {a,b}=={b,a} > > Is it really true? What's about x=0? > > Regards > F. Mittermayr > Because of In[1]:= x^2/x Out[1]= x This is formal algebra that ignores special cases. It takes the generic situation like Solve with In[2]:= Solve[y x == 1, y] Out[2]= {{y -> 1/x}} Whereas we get In[3]:= Reduce[y x == 1, y] Out[3]= y == 1/x && x != 0 Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565