Search code examples
algorithmnumerical-methods

Obtaining the functional form of a curve


The following is the plot of a curve f(r), where r is the radial coordinate, and plotted for different values of a parameter as shown:

plot

However, I don't know the functional form of the curve and I am interested to find the same. Are there any numerical methods which can be used to find the functional form of f(r) in terms of the radial coordinate and the parameter?


Solution

  • I had found a solution of the problem based on the suggestion by ja72 to use the Eureqa software which churns through the data to create accurate predictive models using evolutionary search algorithm.

    In the question, the different curves corresponds to different values of eqn5. So, initially I obtained the best fit equation for different values of eqn8 and found that the following model equation is suitable for my purpose:

    eqn1

    Then, I repeated the process for a large number of values of eqn9 and calculated the values of the four functions eqn2 for different values of eqn4 and then individually fitted these four functions. The following are the results that I obtained:

    eqn3

    N.B.: Eureqa gave several other better fitting formulas than those mentioned in the answer. But the formulas that I mentioned are sufficiently accurate for my purpose and have minimum complexity.