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Re: Applying Math 6

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82338] Re: Applying Math 6
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Thu, 18 Oct 2007 04:46:25 -0400 (EDT)
  • References: <ff4etv$dcu$1@smc.vnet.net>

Hi,

model[x_, a_, bc_, be_, d_, f_] :=
  Exp[-(a*Log[x])/bc]^d + Exp[-a*Log[x]/be]^f

make some test data

With[{f = 1.5, d = 1.33, a = 1, bc = 2, be = 2.1},
  data = Table[{x,
      model[x, a, bc, be, d, f] + RandomReal[{-0.01, 0.01}]}, {x,
      0.0001, 10, 0.01}];
  ]
fit the data

fit = FindFit[data ,
   model[x, a, bc, be, d, f], {a, bc, be, d, f}, x]

and draw the result

Plot[
  model[x, a, bc, be, d, f] /. fit, {x, 0.001, 10}, Frame -> True,
  Epilog -> {Point[data]}]

Regards
   Jens

Johan Mars wrote:
> Dear Users,
> I need to fit x-y data to the equation below and also need to determine
> the derivative.
> Please help.
> 
> y=exp[-(a*ln(x))/bc]^d + exp[-(a*ln(x)/be]^f
> 
> This equation is used in adsorption studies and is normally referred to
> as the Dubinin-Izotova equation.
> 
> 
> 
> Sincere regards
>  
> Dr. Johan Mars
> Environmental Awareness         Tel.: +27 21 9593050
> Department of Chemistry             Fax.: +27 21 9593055
> University of the Western Cape     Cell.:+27 72 5043585
> Private Bag X17
> Bellville, 7535
> South Africa
> http://www.uwc.ac.za 
> 


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