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Article #87Re: HELP REQUEST: Need good method to solve equations of (exp(x)>x) type
From: Warren
Date: Wed, 30 Apr 1997 00:00
Date: Wed, 30 Apr 1997 00:00
47 lines
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2738 bytes
Stefano, A good book on solving these types of equations iteratively is Burden and Faires, Numerical Analysis. I have the 2nd and 3rd editions, but I think there may be a later edition. They discuss several methods. The method you are using might fit into something called the bisection method. Nothing at all wrong with the method except it could take some time. There is also a method called the Newton-Raphson method to find the solution of f(x)=0. For Calculus students, this would be a great example to tie some of the concepts together. Burden and Faires introduce the method using a Taylor series expansion so that f(x)+(x-x_bar)f'(x_bar) ~~ 0, assuming the function is twice differentiable on some closed set and ignoring the error term. Guess at the solution then iterate until some convergence criteria is met. The iterative relationship is p_n = p_n-1 - f(p_n-1)/f'(p_n-1). baro@pt.tizeta.it (Stefano Baraldi) wrote: >Hi all! > >I'm going to give my Calculus exam next month, i still have real >doubts about solving equations of this type (i don't knoe their exact >name) > >exp(x)>x, ln(x+a)<tan(x), .... > >and so on... >I know the solution should be found graphically, please could you >point me to books (available online) or tell me the method to do it? > >Up to now i made a simple comparing algorithm on my sci-calculator, >but that's not so ortodox.. :)) > >thank you and bye! > >See ya, >--------------------------------------------------------------------------------- > ------<<<<<< T H E B A R D >>>>>>------ >--------------------------------------------------------------------------------- >
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f458d,6010e1b8740e33f7 X-Google-Attributes: gidf458d,public X-Google-Thread: 10d632,6010e1b8740e33f7 X-Google-Attributes: gid10d632,public X-Google-Thread: 10c033,6010e1b8740e33f7 X-Google-Attributes: gid10c033,public X-Google-Thread: fad1e,6010e1b8740e33f7 X-Google-Attributes: gidfad1e,public X-Google-Thread: 10d67e,6010e1b8740e33f7 X-Google-Attributes: gid10d67e,public X-Google-Thread: 1077c2,6010e1b8740e33f7 X-Google-Attributes: gid1077c2,public X-Google-Thread: 109d8a,6010e1b8740e33f7 X-Google-Attributes: gid109d8a,public From: Warren <wlmay@umsmed.edu> Subject: Re: HELP REQUEST: Need good method to solve equations of (exp(x)>x) type Date: 1997/04/30 Message-ID: <5k7kdp$6c8$1@www.umsmed.edu> X-Deja-AN: 238420965 References: <5k5u04$kv2$1@qualcuno.nettuno.it> Organization: University of Mississippi Medical Center Newsgroups: alt.uu.math.misc,aus.mathematics,sci.math,sci.math.symbolic,sci.stat.math,ucb.math,uk.education.maths