# Jiles–Atherton parameters

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ANANTA BIJOY BHADRA on 2 Feb 2022
Answered: Anshuman on 29 Jan 2024
How can I calculate Jiles-Atherton parameters. What will be the equations and how to write them in MATLAB code. can anyone give me code or suggestions?
Rik on 3 Feb 2022
I don't think this is a Matlab problem yet. Would you be able to explain with pen and paper how to do it? You need to explain the actual Matlab problem, otherwise you reduce the number of people who can help you to only those who understand this specific problem as well.

Anshuman on 29 Jan 2024
Hi Ananta, the core equations of the Jiles-Atherton model describe the relationship between the magnetization ( M ), the applied magnetic field ( H ), and the anhysteretic magnetization ( M_a ). The Jiles-Atherton model parameters are:
• ( M_s ): Saturation magnetization
• ( a ): Exchange coupling constant
• ( k ): Anisotropy constant
• ( c ): Magnetization reversal constant
• ( alpha ): Parameter representing losses due to eddy currents and other effects
To calculate the Jiles-Atherton parameters, you typically perform a nonlinear curve fitting to experimental data. This can be done using MATLAB's optimization toolbox, specifically the "lsqcurvefit" function or similar. Here's a sample code of how you might set this up in MATLAB:
% Experimental data (H: applied magnetic field, M_exp: measured magnetization)
H = [...]; % Applied magnetic field vector
M_exp = [...]; % Measured magnetization vector
% Initial guesses for Jiles-Atherton parameters
params0 = [Ms0, a0, k0, c0, alpha0];
% Define the Jiles-Atherton model equation as a function
JA_model = @(params, H) ... % Implement the Jiles-Atherton equations here
% Set options for the fitting algorithm
options = optimoptions('lsqcurvefit', 'Display', 'iter', 'Algorithm', 'trust-region-reflective');
% Perform the curve fitting to find the best parameters
[params_fit, resnorm, residual, exitflag, output] = lsqcurvefit(JA_model, params0, H, M_exp, [], [], options);
% Extract the fitted parameters
Ms_fit = params_fit(1);
a_fit = params_fit(2);
k_fit = params_fit(3);
c_fit = params_fit(4);
alpha_fit = params_fit(5);
This is a general outline of how you can calculate Jiles-Atherton parameters using MATLAB.