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Re: Integer Solutions

• To: mathgroup at smc.vnet.net
• Subject: [mg76991] Re: Integer Solutions
• From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
• Date: Thu, 31 May 2007 03:27:09 -0400 (EDT)
• Organization: The Open University, Milton Keynes, UK
• References: <f3jh5v$dda$1@smc.vnet.net>

Jeff Albert wrote:
> I need to find integer solutions for k in terms of t and d in the following
> expression:
> 
> k/(-((t - Log[E^t + d*k])/d)).
> 
> Does Mathematica have any magic that will do this?
> 
> Jeff A

Jeff,

Your request is not clear enough. You said you wanted to find a solution 
to a expression; however, an expression without any ==, <, <=, >, or >= 
symbol is neither an equation nor an inequality, so it is not solvable.

You should provide a complete expression, say

k/(-((t - Log[E^t + d*k])/d)) == 0

Then, you could use Reduce, for instance, as in

In[1]:=
expr = k/(-((t - Log[E^t + d*k])/d)) == 0;
Reduce[expr, k, Integers]
Reduce[expr, k, Complexes]

Out[2]= False

Out[3]= t - Log[E^t] != 0 && (d == 0 || k == 0)

Regards,
Jean-Marc