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MathGroup Archive 2007

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Re: Applying Math 6

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82355] Re: Applying Math 6
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Thu, 18 Oct 2007 04:55:08 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <ff4etv$dcu$1@smc.vnet.net>

Johan Mars wrote:

> 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.

To help you started with Mathematica syntax, the first expression 
defines a function and the second expression takes the first derivative.

In[1]:= y[x_] := Exp[-(a*Log[x])/bc]^d + Exp[-(a*Log[x])/be]^f

In[2]:= y'[x]

Out[2]=
        -1 - a/bc   -(a/bc) -1 + d         -1 - a/be   -(a/be) -1 + f
   a d x          (x       )          a f x          (x       )
-(-------------------------------) - -------------------------------
                 bc                                 be

Regards,
-- 
Jean-Marc


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