What are some alternatives to least squares method?

Question

I am now working on sir model for epidemic modeling and I am trying to estimate the parameters of the system using available data,but I have to approximate the points representing the variables with respect to time. So apart from the least squares method, what are some other methods that could solve this problem ?

Answer 1

gradient descent https://en.wikipedia.org/wiki/Gradient_descent is an universal method to approximate any function or dataset