In what way, if any, is a model different from a simulation?

The editing of digital photos us about the same level of difficulty as editing an analog photo

Least square fit to polynomial write a function leastsquarefit3pol that solves a linear system of equations to find a least squares fit of a third order polynomial to an experimental data set given as two row arrays. the function leastsquarefit3pol must explicitly solve a set of linear equations and cannot use polyfit. there should be no restriction on the size of the problem that can be solved.

Which of the following would you find on a network