Mapping Functions Visual
Visualizing how a function maps points on the number line and its fixed points
This visualization shows how the number line (in red) is mapped by the function
$$ f(x) = 1 + \frac{1}{x} $$
to produce the points shown in green.
The orange lines indicate the fixed points of $f$, which satisfy
$$ x = f(x). $$
We can find these fixed points by solving the equation:
$$ x = 1 + \frac{1}{x} $$
Rearranging,
$$ x - 1 - \frac{1}{x} = 0 $$
Multiplying both sides by $x$ to clear the denominator:
$$ x^2 - x - 1 = 0 $$
The solutions to this quadratic are the fixed points of the function. Fixed points are where applying the function $f$ does not change the point, i.e., $x = f(x)$. In this case, the fixed points are the golden ratio and its conjugate.