At a Glance - I Like Abstract Stuff; Why Should I Care?
We're used to functions that eat numbers and spit out other numbers. The function
f (x) = x2
eats a number and spits out the square of that number. For example,
f (4) = 16.
There are also vector functions that may eat and/or spit out multiple numbers. The function
f (u, v) = + v, u – v>
eats two numbers and spits out a vector. For example,
f (2, 3) = <2 + 3, 2 – 3) = <5, -1>.
Now, for extra fun, there are functions that eat functions and spit out other functions! The act of taking a derivative is one example.
We can think of as a function that eats a function and spits out the derivative of that function (which is itself a function):
For example, if we feed the function f (x) = x2 to the function we get
The function ate the function f (x) = x2 and spit out its derivative function, f '(x) = 2x.