Re: a simple question

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• Subject: [mg131734] Re: a simple question
• From: "Barrie Stokes" <Barrie.Stokes at newcastle.edu.au>
• Date: Wed, 25 Sep 2013 02:37:06 -0400 (EDT)
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```Hi Murray

A neat and simple answer to a simple question, and as always with yourself and a few other MathGroup regulars, very helpful.

I can't help feeling, though, every time I see a question of this type ("I am beginner for Mathematica"), that the poster has not even tried to look into the Help.
In real life when I'm asked a question like this, my first response is usually to say, "Show me what you've tried."

Or else I would be tempted to answer, somewhat in the Bob Hanlon style, "See http://reference.wolfram.com/mathematica/ref/Solve.html";.

As I've said more than once before in a similar MathGroup gripe, "Give a man a fish, feed him for a day; teach a man to fish, feed him for a lifetime". (Lao Tzu, apparently.)

Best wishes

Barrie

>>> Murray Eisenberg <murray at math.umass.edu> 09/24/13 6:17 PM >>>
Do you mean you want to solve that equation for h? (That's a different thing than "evaluating it", which would not be possible since the left hand side is not the sort of expression to which you can assign a value -- and what  does is to assign a value. Whereas == denotes an equality.)

Perhaps you mean something like the following:

Solve[A Log[h]/h - x == 0, h]

The result you'll get gives the solution as:

h -> -((A*ProductLog[-(x/A)])/x

This may or may not be of use to you, since ProductLog is a not an "elementary" function.

Do A and x have some specific values?

By the way, it's a bad idea to use names in Mathematica that are, or begin with, an upper-case letter -- because that risks confounding them with the names of built-in objects.

On Sep 23, 2013, at 9:59 PM, Dhaneshwar Mishra <dhaneshwarmishra at gmail.com> wrote:

>
> I would like to evaluate A*Log[h]/h -x=0 for h, can any body help me doing so?
>
> I am beginner for Mathematica.

---
Murray Eisenberg
murray at math.umass.edu
Mathematics & Statistics Dept.