Index mapping for prime factor algorithm of discrete cosine transform

Abstract

This paper provides a direct derivation of the prime-factor-decomposed computation algorithm of an N-point discrete cosine transform for the number N decomposable into two relative prime numbers. It also presents input and output index mappings in the form of tables-namely, ri-, it-, nc-, nK-, and k-tables. The index mapping tables are useful for practical use of the prime-factor-decomposed computation of arbitrarily sized discrete cosine transforms.