I think this is overdone and does not help the intuition. two things: (1). the first step of transposing the second matrix 90 degree is unnecessary and confusing. A row vector and a column vector are different. This step confuses the two. (2). All the final elements are independent and should be calculated in parallel, the stepped anime is not necessary and does not reveal this basic fact.
stock price is about the sum of all future cash flow. not current profit level. you can have different forecasts, but you cannot say the act of making forecast itself is nonsense.
Definition 5.1/5.2 is interesting. It defines derivative at point c, not the derivative function of f. Note that f1(x) is not equal to f'(x) for all x, but f1(c) = f'(c).
There is a big gap between chapter 1 and chapter 3, which makes me doubt this book is very unrealistic. In chapter 1, it argues kids cannot follow logic, it is not trivial for them to understand the counting with rearrangement; in chapter 3, they suddenly can count c(5,2), and they even can understand this number by using symbols URR.., which requires an algebraic mind.
don't be fooled by the title of the book. The content is beyond 7 year old kids in the US.
People use R as a convenient tool.i.e., R users are tool/library users, not tool builders in general. Haskell cannot compete with R for this user base.