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MathGroup Archive 2007

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Re: Curve-fitting/data analysis question...

  • To: mathgroup at smc.vnet.net
  • Subject: [mg73324] Re: Curve-fitting/data analysis question...
  • From: dh <dh at metrohm.ch>
  • Date: Mon, 12 Feb 2007 05:03:42 -0500 (EST)
  • References: <eqmcfh$bdv$1@smc.vnet.net>


Hi noname,

here is an example:

fun = x1 Exp[-x3(x - x2) Boole[x > x2]];

res = FindFit[d, fun, {x1, x2, x3}, x]

funr = fun /. res;

Plot[funr, {x, 0, 2}]

Daniel



sherifffruitfly wrote:

> Hi all,

> 

> I've got some data that is approximately constant, c, over an

> interval, and then drops off like -(a exp(b x)).

> 

> How can I determine when the constant part ends, and the negative

> exponential begins in Mathematica? I can eyeball it on a graph, but I'd much

> prefer to have a principled Mathematica routine settle the question. Once

> that's settled, it should be straightforward to determine the

> exponential's parameters via some curve-fitting routine or other.

> 

> Thanks for any suggestions,

> 

> cdj

> 

> 




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