9.3 Summary
Now that we’ve learned what functions really are, I bet your world is a bit shaken. Functions as graphs drawn with continuous lines, sure. Maybe even expressions like f(x) = x2 + 1. But functions as dots and arrows?
Surprisingly, the dot-and-arrow representation is the closest to the true definition. Graphs and expressions come after that. This is what we’ve learned in this chapter, and by now, I feel like a magician. I’ve shown you mathematical objects and revealed that, deep inside, they are not what you think. We did this with vectors, matrices, and now, with functions.
Along with the “what’s behind the curtain?” tricks, putting theory into practice also became an established pattern for us. So, we’ve used object-oriented Python to get a taste of what a function is like.
Next, we’ll turn our lenses to an even higher level of magnification. For us, the most important functions map numbers to numbers. But what’...
