UseNPtoWriteLinarRegression

1. There are multiple ways to write linar regression code in python, basically, we can calculate w * x one by one.
  We also can use for loop to calculate it.
  But the best way is use numpy.dot(x,w) to caculate. It will return the sum of w*x.
2. NumPy is a great package for machine learning. Also it is great for vector calculate.
3. What is normal equation?
  The "normal equation" is a term used in linear algebra and statistics, particularly in the context of linear regression. It provides a method to find the best fitting line to a set of points in a linear regression model. This best fitting line is determined by minimizing the sum of the squared differences between the observed values and the values predicted by the line.
4. We can also use numpy to calculate the cost function