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dpi
Posts:
2
Registered:
3/3/13


'Power Law with singularity' regression  error
Posted:
Mar 3, 2013 10:57 PM


Hi,
I am testing the "Power Law with finitetime singularity" hypothesis for the World population growth for a project.
For that I was trying the following model:
model = A + B*(c  x)^z;
And then the following curve fit method:
FindFit[data, {model}, {A, B, c, z}, x]
But I always get the result:
Power::indet: "Indeterminate expression 0.^0. encountered." FindFit::nrjnum: "The Jacobian is not a matrix of real numbers at {A,B,c,z} = {1.,1.,1.,1.}. " {A > 1., B > 1., c > 1., z > 1.}
If I do a normal Power law regression, FindFit works perfectly, but the title of the project being "Power Law with finitetime singularity" I need to have a singularity in the model and the main aim is to find when this singularity occurs.
Is there a way to use 'FindFit[]' to get the correct answer? Or Should I be using some other function?
I have seen other articles on this site concerning issues with FindFit, but none of them has helped me resolve this problem.
Thanks for the help!



