**48. A Transformada Discreta do Cosseno
em um Corpo Finito**

A new digital transform, the discrete cosine transform in a finite field
(FFDCT) is introduced.

The kernel of the FFDCT is the trigonometric function cosine defined over
a finite field.

A new property of such functions is established, through which an inversion
formula for the FFDCT is derived.