Re: Why does the order of down values come back?
- To: mathgroup at smc.vnet.net
- Subject: [mg124797] Re: Why does the order of down values come back?
- From: David Reiss <dbreiss at gmail.com>
- Date: Tue, 7 Feb 2012 04:03:48 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <jgo0e9$a2k$1@smc.vnet.net>
Options[DownValues]={Sort->True}
--David
On Feb 6, 2:45 am, Shizu <slivo.v... at msa.hinet.net> wrote:
> In[]:= f[0] := 0;f[1] := 1;f[n_] := f[n - 1] + f[n - 2]
>
> In[]:= DownValues[f]
> Out[]:= {HoldPattern[f[0]] :> 0, HoldPattern[f[1]] :> 1, HoldPattern[f[n_]] :> f[n - 1] + f[n - 2]}
>
> In[]:= DownValues[f] = Reverse[DownValues[f]]
> Out[]:= {HoldPattern[f[n_]] :> f[n - 1] + f[n - 2], HoldPattern[f[1]] :=
> 1, HoldPattern[f[0]] :> 0}
>
> In[]:= DownValues[f]
> Out[]:= {HoldPattern[f[0]] :> 0, HoldPattern[f[1]] :> 1, HoldPattern[f[n_]] :> f[n - 1] + f[n - 2]}
>
> =========================
> My question is:
>
> Why does the order of down values comes back after reordering?
>
> Thanks.