Maths > Functions > 5.0 Standard Real Functions and their Graphical Representation

  Functions
    1.0 Definitions
    2.0 Relation
    3.0 Types of Relation
    4.0 Functions
    5.0 Standard Real Functions and their Graphical Representation
    6.0 Operations on Real Functions
    7.0 Types of Functions
    8.0 Composition of a Function
    9.0 Inverse of a Function

5.6 Fractional Part Function
For any real number $x$, the fractional part or decimal part of $x$ is denoted as, $$\left\{ x \right\}$$
Here, $$f(x) = \;\left\{ x \right\} = x - \left[ x \right]\;,\;\forall \;x \in R$$
For example: Let us assume the value of $x=4.9$ in a function $y = \left\{ x \right\}$. We can write $4.9$ as
$$\begin{equation} \begin{aligned} 4.9 = 4 + 0.9 \\ x = \left[ x \right] + \left\{ x \right\} \\ \Rightarrow \left\{ x \right\} = 0.9 \\ \therefore \left\{ x \right\} = x - \left[ x \right] \\\end{aligned} \end{equation} $$
To plot the graph, we can write the fractional part of $x$ as $$y = \left\{ x \right\} = x - \left[ x \right]$$
Now, let us divide the intervals of $x$ and find value of $y$.

$y=x-[x]$$x$
$x+3$$ - 3 \leqslant x < - 2$
$x+2$$ - 2 \leqslant x < - 1$
$x+1$$ - 1 \leqslant x < 0$
$x$$0 \leqslant x < 1$
$x-1$$ 1 \leqslant x < 2$
$x-2$$2 \leqslant x < 3$
$x-3$$ 3 \leqslant x < 4$


Using the values we get in the table, plot the graph in the corresponding intervals of $x$.


From the graph, we can conclude that, it is a periodic function with period $1$.
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