IRLS
[Newton–Raphson method](https://texonom.com/newtonraphson-method-0bc249bfb0fe4e498829110bf785eb6c) 


### **Iterative Re-weighted Least Squares**
Iterative re-weighted least squares (IRLS) is an optimization algorithm used to solve nonlinear least squares problems. It is an iterative algorithm that updates the solution in each step until convergence is achieved. In each iteration, the algorithm re-weights the observations based on the current estimate of the solution. This makes the algorithm more robust to outliers and can help it converge more quickly.
update rule is similar with










