       • To: mathgroup at smc.vnet.net
• From: Tomas Garza <tgarza01 at prodigy.net.mx>
• Date: Tue, 11 Feb 2003 04:42:19 -0500 (EST)
• References: <200302100608.BAA23852@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```The problem seems to be that t doesn't have x as an explicit argument. Try
the following (which can perhaps be further simplified):

In:=
f[x_] := x^2 - 2;
Ne[x_] := x - f[x]/f'[x];
ap = NestList[Ne, 1.5, 5];

In : =
Clear[tang];
tang[h_, x_] : = f[h] + f'[h] (x - h);

In:=
Plot[Evaluate[Table[tang[ap[[j]]*j, x],
{j, 1, Length[ap]}]], {x, -10, 10},
PlotRange -> {{-5, 5}, {-3, 5}}];

Tomas Garza
Mexico City
----- Original Message -----
From: "baruch" <spin9 at terra.com.br>
To: mathgroup at smc.vnet.net

> 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!
>
>

```

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