Re: Don't understand Plot behavior

• To: mathgroup at smc.vnet.net
• Subject: [mg39995] Re: Don't understand Plot behavior
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Fri, 14 Mar 2003 04:45:35 -0500 (EST)
• Organization: Universitaet Leipzig
• References: <b4pf6u\$bu4\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi,

yes because Evaluate[] work only if it is
waraped arround a function argument or a
sequence of arguments, and you have to write

Plot[Evaluate[{f[t],0}] , {t, 0, 1}]

otherwise the List[] argument is evaluatet that
help Plot[] nothing.

Regards
Jens

Alain Cochard wrote:
>
> In[1]:= f[t_]:= D[t  , t]
>
> In[2]:= Plot[Evaluate[f[t]] , {t, 0, 1}]
>
> Out[2]= -Graphics-    [The plot is fine]
>
> In[3]:= Plot[{Evaluate[f[t]],0} , {t, 0, 1}]
>
>                          -8
> General::ivar: 4.16667 10   is not a valid variable.
>
> [...]
>
> General::stop: Further output of General::ivar
>      will be suppressed during this calculation.
>
> Plot::plnr: Evaluate[f[t]] is not a machine-size real number at t =
>               -8
>     4.16667 10  .
>
> [...]
>
> General::stop: Further output of Plot::plnr
>      will be suppressed during this calculation.
>
> Out[3]= -Graphics- [The plot just shows the axes]
>
> In[4]:= harhar=Evaluate[f[t]]; Plot[{harhar,0} , {t, 0, 1}]
>
> Out[4]= -Graphics- [The plot is fine]
>
> In[5]:= \$Version
>
> Out[5]= 4.1 for Sun Solaris (November 8, 2000)
>
> Is this behavior normal?  Thx in advance.
>
> Alain Cochard
> al2 at noos.fr

```

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