       Re: Non-algebraic solution

• To: mathgroup at smc.vnet.net
• Subject: [mg52492] Re: Non-algebraic solution
• From: Peter Pein <petsie at arcor.de>
• Date: Mon, 29 Nov 2004 01:22:45 -0500 (EST)
• References: <co6h5d\$nmp\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```B.Ravinder wrote:
> Dear all,
> I want to plot the following type of logarithmic equation having
> dependent variable y and independent variable x.
>
> Log[y/a] + b*Log[c+y/d] = -x
>
> where a,b,c and d are some arbitrary constants.
>
> First I tried to solve the equation for y using Solve function in
> Mathematica 4.2, but got the following error
> message:
> Solve:: tdep :
> The equations appear to involve the variables to be solved
> for in an essentially non-algebraic way.
>
>
> Could someone please guide me as to how do we solve such equation
> with/without Mathematica.
>                              or
> If possible, how to obtain y vs. x plot in Mathematica without soving them
> exactly.
> Waiting for the kind resonse.
>
> Regards,
> Ravi
>
I really wonder why nobody got the idea to use ParametricPlot?

ParametricPlot[{-Log[y/a] - b*Log[c+y/d],y},
{y,y1,y2}(*desired y-Range*), PlotRange->{{x1,x2},{y1,y2}}]

looks simple to me. Did I miss something?

--
Peter Pein
10245 Berlin

```

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