Definition:Number Base/Radix Point

Definition
Let $x \in \R$ be a real number such that $x \ge 0$.

Let $b \in \N: b \ge 2$.

In the basis expansion:
 * $x = \sqbrk {r_m r_{m - 1} \ldots r_2 r_1 r_0 \cdotp d_1 d_2 d_3 \ldots}_b$

the dot that separates the integer part from the fractional part is called the radix point.