/*DCT和IDCT快速变换的C语言实现



仿效FFT的FDCT方法有与DCT无关的复数运算部分，选用代数分解法可以降低运



算量，达到高速运算的目的。代数分解法实现如下：对一维DCT表达式直接展开，



寻找各点表达式中共同项，仿FFT蝶形关系，将表达式中的共同项作为下一级节



点，依次进行多次，最后得到变换结果。*/-/ * DCT and IDCT rapid transformation of C language FFT follow the diagram method with DC T unrelated to the complex computing, use algebraic decomposition method can reduce the amount of computation and high-speed computing to achieve the purpose. Algebra factorization method is as follows : one-dimensional DCT direct expression start to find points of common expression, imitation FFT butterfly, expression of the common items as under a node, followed by a number, finally transform results. * /