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Hi
I would like to fit some measured magnetisation data using an integral of the Langevin formula multiplied by log normal. I am new to writing functions to fit, so I wanted to try by just re-writing the Langevin formula but I can't even get this to work!
I want to use something of the form M = Ms*((cosh(A*r*H)/sinh(A*r*H))-1/A*r*H) where H is the dependent variable and r is varied to give the best fit to the data. I have defined Ms=4.8E5, A=6.1E20, r = 9e(-9). When I try to evaluate this in the function builder it doesn't give me a value, and when fitting it does not produce a fit that converges.
The definition itself seems correct. I don't know the range of H (which is, I guess, an independent variable, not dependent, and M is), but for example, when H=1e-50, your function returns 8.7431693989071E42 .
Integrating the Langevin formula
Posted - 09/18/2013 : 12:00:39 PM
