Matrices in the Machine

No matter what we consider the internal representation, the data will be stored linearly in memory. If we are using a programming language like C, we would use something like this to define a two-dimensional array for a 2×2 matrix: Now, there’s a lot of different ways to represent this,

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Zeroes Are Hard to Find

When we are looking at two-dimensional optimization algorithms, there are a variety of options. The first is the bisection method. I like the bisection method, because it makes a delightful use of the intermediate value theorem. We can use the fact that continuous functions take on all of the values

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NaN versus NA in R

R has two different ways of representing missing data and understanding each is important for the user. NaN means “not a number” and it means there is a result, but it cannot be represented in the computer. The second, NA, explains that the data is just missing for unknown reasons.

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