Re: To plot solutions, FindRoot as a function

• To: mathgroup at smc.vnet.net
• Subject: [mg37380] Re: [mg37341] To plot solutions, FindRoot as a function
• From: Tomas Garza <tgarza01 at prodigy.net.mx>
• Date: Fri, 25 Oct 2002 02:48:44 -0400 (EDT)
• References: <200210240655.CAA05094@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

Well, yes, perhaps a bit too naive. Bear in mind that 1) a 3D plot needs
Plot3D; 2) The result of FindRoot is in the form of a rule wherefrom you
have to extract the actual value you need. Try this:

In[1]:=
sol[a_, b_] := FindRoot[a*Tanh[b*x] == x,
{x, {0.01, 0.1}}]

In[2]:=
Plot3D[sol[a, b][[1,2]], {a, 1, 2}, {b, 1, 2}];

Tomas Garza
Mexico City

----- Original Message -----
From: "Veniamin Abalmassov" <V.Abalmassov at unibas.ch>
To: mathgroup at smc.vnet.net
Subject: [mg37380] [mg37341] To plot solutions, FindRoot as a function

> Hello,
>
> I'd like to plot the solution of an equation which depends on two
> parameters, e.g.
>
> a*Tanh[b*x] == x
>
> So, I'd like to see it in 3D, one axis is "a", other is "b", and the last
> is "solution".
>
> I've tried naively to do it as follows:
>
> sol[a_,b_]:=FindRoot[a*Tanh[b*x] == x, {x, {0.01, 0.1}}]
> Plot[sol[a,b], {a, 1, 2}, {b, 1, 2}]
>
> And it doesn't work. Help me, please. What can I do?
>
> Thanks a lot,
>
> Veniamin
>
>
>
>

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