*To*: mathgroup@smc.vnet.net*Subject*: [mg12030] RE: [mg11966] [mg11966] calculation*From*: "jmt" <jmthomas@cybercable.tm.fr>*Date*: Fri, 24 Apr 1998 01:52:03 -0400

Try this: First define a function to help investigate the behaviour of your equation: f[R_]=.001422409738*R^(73/80)*(R^(1/2)-1)^(-13/40) - .04 Plot the function (I used Re because for R<0 f is complex) with different ranges for R: Plot[Evaluate@Re@f[R],{R,50,100}] After three tests, the range {R,50,100} seems to lead to something, you can then use FindRoot[f[R]==0,{R,80}] where 80 is a starting value. {R\[Rule]81.2654929724756414`} Of course, this is a numerical solving only: you have no garantee of other roots, and no symbolic expression. But your data seems numerical, isn't it? Hope this helps **************************************** Jean-Marie THOMAS Conseil et Audit en Inginierie de Calcul Strasbourg, France **************************************** -----Original Message----- From: Saeed Esmaily Rashid [mailto:saeedr@stud.ntnu.no] To: mathgroup@smc.vnet.net Subject: [mg12030] [mg11966] [mg11966] calculation Hello! 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? Regards