Create a sinus cardinalis function in the form $f(x)=a·sin(fx-o)/x+c$.

Input parameters:

1. a → Amplitude of sinc wave.
2. f → Frequency of sinc wave, as a multiple of $2\pi$.
3. o → Horizontal offset of sinc wave.
4. c → Vertical offset of sinc wave.

Output parameters:

1. Fn → Sinc function in the form $f(x)=a·sin(fx-o)/x+c$.