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To read a book like Elements of Statistical Learning what are the mathematical prerequisites. I currently know Linear Algebra ( basic course ) , single variable and multiple variable calculus. I want to become a data scientist and for that I require strong mathematical background. Various sites say that courses on optimization like Convex optimization are really important. Now the point is I have no mentor so to say, I have to read on my own. I checked out the stanford course on convex optimization. It said that real analysis was not a prerequisite but if you have done it it will be useful. So my question in a way is, how useful is "real analysis" for a data scientist. And if I know Linear Algebra, single and multivariable calculus, then what are the next things in data science that I should venture into ?