Re: Bug in Simplify?
- To: mathgroup at smc.vnet.net
- Subject: [mg33235] Re: Bug in Simplify?
- From: "Steve Durbin" <steved at vale.demon.co.uk>
- Date: Sat, 9 Mar 2002 18:05:21 -0500 (EST)
- References: <a61v7q$gpt$1@smc.vnet.net> <a64fu0$n04$1@smc.vnet.net> <a675en$d0m$1@smc.vnet.net> <a6chk6$dr0$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
"David W. Cantrell" <DWCantrell at sigmaxi.org> wrote in message news:a6chk6$dr0$1 at smc.vnet.net... > If you really want some things to ruffle your feathers, try the following: > > Simplify[0/x, x==0] > Simplify[x/y, x==0 && y==0] > Simplify[x/x, x==0] > > The results are 0, 0, and 1, resp., which I consider as being closer to > "crimes" than "misdemeanors". It gets worse than that :-( Simplify doesn't agree with the rest of the kernel: In[1]:= a = Simplify[0/x, x == 0]; b = Simplify[x/y, x == 0 && y == 0]; c = Simplify[x/x, x == 0]; Print["0/x=", a, " x/y=", b, " x/x=", c] Out[1]:= 0/x=0 x/y=0 x/x=1 In[2]:= (* will give errors without Off[Power::infy]; *) (* and Off[\[Infinity]::indet]; *) x = 0; y = 0; a = 0/x ; b = x/y ; c = x/x; Print["0/x=", a, " x/y=", b, " x/x=", c] Out[2]:= 0/x=Indeterminate x/y=Indeterminate x/x=Indeterminate So 0/0 is assumed to be either 0, 1 or indeterminate depending on which input form is used. Also, the second form gives warnings about the problem, whereas the first doesn't. Cheers, -- Steve Durbin | Look! Minimalism comes to ASCII art! | .