According to "Constructible function", Wikipedia:
In complexity theory, a time-constructible function is a function f from natural numbers to natural numbers with the property that f(n) can be constructed from n by a Turing machine in the time of order f(n).
But $\log\left(n\right)$ doesn't map onto natural numbers but to real numbers.
Why is $\log\left(n\right)$ nevertheless a space-constructible function?