• To: mathgroup at smc.vnet.net
• From: Fernando Ortega <fortega at pcb.ub.es>
• Date: Tue, 11 Feb 2003 04:41:40 -0500 (EST)
• Organization: CESCA - Servidor de news de l'Anella Cientifica
• References: <b27ft7\$nel\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Hi:

you have to use the command Evaluate for evaluating your list t:

Plot[Evaluate[t], {x, -10, 10}]

I hope it works

Fernando

baruch wrote:
> f[x_] := x^2 - 2
> Ne[x_] := x - f[x]/f'[x]
> ap = NestList[Ne, 1.5, 5]
> tang[h_] := f[h] + f'[h](x - h)
> t = tang /@ ap
>
> Plot[{t}, {x, -10, 10}, AxesOrigin -> {0, 0},
>   PlotRange -> {{-5, 5}, {-3, 5}}]
>
> Now, How can I plot the last command?
>
> I got the following errors:
>
> Plot::"plnr": "\!\(te[x]\) is not a machine-size real number at
> \!\(x\) = \
> \!\(-9.999999166666667`\)."
> Plot::"plnr": "\!\(te[x]\) is not a machine-size real number at
> \!\(x\) = \
> \!\(-9.188660168541684`\)."
>
> I want to make a "program" that will plot the successives tangent
> lines of approximations of any function (when possible) using the
> Newton Methods... any idea on how can I implement or solve that
> problem?
>
> Thank you very much!
>

```