[Date Index] [Thread Index] [Author Index]

Re: Simple Problem (I suppose...)

• To: mathgroup at smc.vnet.net
• Subject: [mg22118] Re: Simple Problem (I suppose...)
• From: "David Bailey" <db at salford-software.com>
• Date: Wed, 16 Feb 2000 02:34:34 -0500 (EST)
• Organization: University of Salford, Salford, Manchester, UK
• References: <888a2i$c6a@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Andreas Kallmeyer <kallmeyer at bigfoot.com> wrote in message
news:888a2i$c6a at smc.vnet.net...
> Hi!
>
> I just got Mathematica 4 and when I try such easy calculations as below
> and then I can't plot the result.... WHY?? I really have no clue.
>
> Thanks,
>
> Andreas.
>
> Here my text is clipped:
> "
> In[1]:=
> Remove["Global'*"]
>
> Remove::"rmnsm": "There are no symbols matching \"\!\(\"Global'*\"\)\"."
>
> In[2]:=
> \!\(f[\(x\_-\)] := \ x\^5 + x\^4 + x\^2\)
>
> In[3]:=
> Plot[f[x], {x, -10, 10}];
>
> Plot::"plnr": "\!\(f[x]\) is not a machine-size real number at \!\(x\) =
> \
> \!\(-9.999999166666667`\)."
>
> Plot::"plnr": "\!\(f[x]\) is not a machine-size real number at \!\(x\) =
> \
> \!\(-9.188660168541684`\)."
>
> In[4]:=
> \!\(f2[\(x\_-\)]\  = \ \[PartialD]\_x f[x]\)
>
> Out[4]=
> \!\(\*
>   RowBox[{
>     SuperscriptBox["f", "\[Prime]",
>       MultilineFunction->None], "[", "x", "]"}]\)
>
> In[5]:=
> ?f2
>
> In[6]:=
> \!\(f2[x]\  = \ \[PartialD]\_x f[x]\)
>
> Out[6]=
> \!\(\*
>   RowBox[{
>     SuperscriptBox["f", "\[Prime]",
>       MultilineFunction->None], "[", "x", "]"}]\)
> "
>

I think the problem here is that rather than f[x_] you wrote the '_'
character as a subscript of x. BTW, it is better to convert information to
InputForm via the Cell>Convert To  menu item before clipping it into an
email. Indeed, had you done this, the mistake would probably have become
obvious.

David Bailey
Salford Software