Traversing matrices efficiently

Matrices are a basic building block of any numerical computing workflow. In this introductory recipe, we show how to work with them using loops.

The important point to consider here is that in order to traverse a matrix efficiently in Julia you should traverse it column-wise, as this is the memory layout used internally. Other languages that use column-major order are Fortran, MATLAB, and R.

Getting ready

Make sure that you have the BenchmarkTools.jl package installed. If it is missing then run the following command: using Pkg; Pkg.add("BenchmarkTools").

Note

In the GitHub repository for this recipe, you will find the commands.txt file that contains the presented sequence of shell and Julia commands and the sums.jl file that contains definitions of functions used in this recipe.

Now open your favorite terminal to execute the commands.

How to do it...

First, we define two ways we could implement a function that takes the sum of all elements of an array. After this...