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