Adding a best fit curve to a scatter plot

I have a scatter plot consisted of 620 points. I want to set the best fit curve rather than me using the "polyfit" function and then use "polyval". In that case I am the one who changes the degree. I also want to show the equation corresponsing to the best fit curve.

When explaining me the procedure, please use some random numbers to X and Y vectors so I can better understand it.

Thanks,

Thishan

[John D'Errico]

Sorry, but no. Finding the "best" fit curve with no information provided is essentially a search through infinitely many possible model forms. Without intelligent input from the user, this can be virtually impossible.

[John Doe]

This video below explains this absolutely perfectly.

https://www.youtube.com/watch?v=vh1MLk8rLoI