Re: Plotting two functions
- To: mathgroup at smc.vnet.net
- Subject: [mg78340] Re: Plotting two functions
- From: dh <dh at metrohm.ch>
- Date: Thu, 28 Jun 2007 06:28:54 -0400 (EDT)
- References: <f5vsai$kr6$1@smc.vnet.net>
Hi,
if I understand correctly, you can numerically calculate X as a function
of r and you would like to get the inverse r[X]?
The simplest solution is to solve your original equation for r. This
gives: X->(-gamma r-Pp r-beta r^3-Pp r^3-r^5)/(c+delta r^2+alpha r^4)
You can also do it numerically. Calculate some {X,r} pairs covering the
region needed, then feed it e.g. to Interpolation to get r[X].
hope this helps, Daniel
SK wrote:
> Hi
>
> I have a 5th order equation of the form
>
> eqntony445=r^5+(alpha*X)*r^4+(beta+Pp)*r^3+(delta*X)*r^2+(gamma+Pp)*r
> +c*X==0
>
> where alpha, beta, delta and gamma are other combination of terms that
> I havent included for the sake of simplicity.
>
> I can plot X with respect to r for various values of Pp
>
> Plot[Evaluate[Table[X /. Flatten[Solve[eqntony445 == 0, X]], {Pp, 0,
> 20, 5}]], {r, -0.5, 0.5}]
>
> The problem is I have another function of the form
>
> V=Integrate[ ((Pp)/(s)*((r^3+r)/(r^2+1)^2)+2*r,X]
>
> and need to plot it with respect to X. It keeps spitting out stuff of
> the form Root, which is understandable for 5th order equations, but I
> find that if I can plot V with respect to r then there must be a way I
> can take those r values and translate them to X values. Any help will
> be greatly appreciated.
> Thanks
> S
>
>