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Re: calculation

• To: mathgroup@smc.vnet.net
• Subject: [mg12026] Re: [mg11966] calculation
• From: Bob Hanlon <BobHanlon@aol.com>
• Date: Fri, 24 Apr 1998 01:52:01 -0400

In a message dated 4/17/98 3:21:17 AM, saeedr@stud.ntnu.no wrote:

>My name is Saeed and i'm studying physics. I have a problem which ihope
>someone can help me with it. I have an equation
>
>.001422409738*R^(73/80)*(R^(1/2)-1)^(-13/40) == .04
>
>i'm using the Solve function in Mathematica 3.0 to solve it for R, but
>it calculats endlessly and takes very long time. the question is that
>is there any way to optimize this equation or using another function in
>Mathematica 3.0 to make it faster to calculate?


eqn = .001422409738*R^(73/80)*(R^(1/2)-1)^(-13/40) == .04;

Plot[.001422409738*R^(73/80)*(R^(1/2)-1)^(-13/40) - .04, {R, 5, 100}];

FindRoot[eqn, {R, 80.}]

{R -> 81.26549297247551}


Bob Hanlon