Control-drag (or type) the equation $f\left(x\right)\=\dots$

Context Panel: Assign Function

Type the notation for the desired value.

Context Panel: Evaluate and Display Inline

Define the function as shown. The arrow is made with a minus and a greater-than.

$f≔x\to x\cdot \sin \left(x\right)$

Type the notation for the desired value and press the Enter key.

$f\left(\mathrm{\π}\/4\right)$

$f\left(1.3\right)$