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RE: Intersection of sets of results

• To: mathgroup at smc.vnet.net
• Subject: [mg37113] RE: [mg37099] Intersection of sets of results
• From: "DrBob" <drbob at bigfoot.com>
• Date: Thu, 10 Oct 2002 03:20:46 -0400 (EDT)
• Reply-to: <drbob at bigfoot.com>
• Sender: owner-wri-mathgroup at wolfram.com

Those aren't equations; they're functions, and we don't solve functions,
we solve equations.  What equations do you want to solve?

DrBob

-----Original Message-----
From: flip [mailto:flip_alpha at safebunch.com] 
To: mathgroup at smc.vnet.net
Subject: [mg37113] [mg37099] Intersection of sets of results


Hello All,

I have two equations that I have solved for:

x[n_]  := 2331 + 8 n
y[n_] :=  -3108 - 11n

I want to include only solutions which are non-negative, that is x >= 0
and
y >= 0.

In this example we can do 2331 + 8n > = 0 and solve for n, n >= -291.375
and -3108 - 11 n >= 0 and solve for n, n <= -282.545

So we have -291.375 <= n <= -282.545.

The "integer solution set here is for n =
{-290, -289, -288, -287, -286, -285, -284, -283}.

So in this case we have 8 non-negative solutions.

Given that I can supply x[n] and y[n], how do I go about finding the set
n?

Thank you for any inputs, Flip