Re: Undiscovered Bug?
- To: mathgroup at smc.vnet.net
- Subject: [mg46881] Re: Undiscovered Bug?
- From: Roland Franzius <roland.franzius at uos.de>
- Date: Fri, 12 Mar 2004 23:39:29 -0500 (EST)
- Organization: Universitaet Hannover
- References: <c2rnrf$p4h$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Harold Noffke wrote:
> MathGroup:
>
> In Mathematica 5.0.1 with Windows 2000, I mistakenly used the [[{}]]
> operator on x/y. I was expecting an error, but I kept getting unusual
> results as shown in In/Out's 2 to 5 below.
>
> Have I stumbled on a bug, or is there a way to make sense out of this?
>
>
> In[1]:= TreeForm[x/y]
>
> Out[1]//TreeForm= Times[x, | ]
> Power[y, -1]
>
> In[2]:= (x/y)[[{2,2}]]
>
>
> Out[2]= -2
> y
>
> In[3]:= (x/y)[[{1,2,1}]]
>
> 2
> x
> Out[3]= --
> y
>
> In[4]:= (x/y)[[{2, 2, 2, 2}]]
>
> -4
> Out[4]= y
>
> In[5]:= (x/y)[[{2, 1, 1, 0, 2, 2, 0}]]
>
> 2 2
> Times x
> Out[5]= ---------
> 3
> y
Using ??, Help or F1 you will find the explanation
"expr[[ {i1, i2, ... } ]] gives a list of the parts i1, i2, ... of expr."
--
Roland Franzius