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nonlinear equation

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pfl...@dem.uminho.pt

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Apr 16, 2003, 1:59:33 AM4/16/03
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Hello,

Can you help me how to solve a nonlinear equation given by:

x = a*y*ln(b) - a*y*ln(y) + a*y

where a and b are constant parameters.
I know the inital value of x0 and I want to know the value of y.

Can I use Newton's method? How?

Regards,
PF


Ferdinand

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Apr 17, 2003, 3:58:34 AM4/17/03
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You may use NSolve.
see Mathematical methods in Physics and Engineering with Mathematica
crcpress, ISBN 1584884029

Raibatak Das

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Apr 17, 2003, 11:14:08 PM4/17/03
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pf -

here is an example for some arbitrary values of a, b and x

In[1]:= a=5
Out[1]= 5

In[2]:= b=10
Out[2]= 10

In[3]:= x=1
Out[3]= 1

In[4]:= NSolve[x == a y Log[b] - a y Log[y] + a y, y]
InverseFunction::ifun:
Inverse functions are being used. Values may be lost for multivalued
inverses.

InverseFunction::ifun:
Inverse functions are being used. Values may be lost for multivalued
inverses.

Solve::ifun: Inverse functions are being used by Solve, so some
solutions may
not be found.

Out[4]= {{y -> 0.0292658}, {y -> 26.9821}}

hope this helps.
- rd
pfl...@dem.uminho.pt wrote:

------------------------------------------------------------------------
* /Raibatak Das / *
Department of Chemistry and Chemical Biology, Cornell University.
Ithaca, NY 14853.
Ph : 1-607-255-6141
email : rd...@cornell.edu <mailto:rd...@cornell.edu>


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