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这些代码是 Numerical Analysis Library 这个函数库里的
(见 https://people.sc.fsu.edu/~jburkardt/f_src/nms/nms.html)
原来的代码中有以下注释:
! WSAVE A REAL WORK ARRAY WHICH MUST BE DIMENSIONED AT LEAST 4N+1
! IN THE PROGRAM THAT CALLS CFFTF. THE WSAVE ARRAY MUST BE
! INITIALIZED BY CALLING SUBROUTINE CFFTI(N,WSAVE) AND A
! DIFFERENT WSAVE ARRAY MUST BE USED FOR EACH DIFFERENT
! VALUE OF N. THIS INITIALIZATION DOES NOT HAVE TO BE
! REPEATED SO LONG AS N REMAINS UNCHANGED THUS SUBSEQUENT
! TRANSFORMS CAN BE OBTAINED FASTER THAN THE FIRST.
! THE SAME WSAVE ARRAY CAN BE USED BY CFFTF AND CFFTB.
这个 wsave 是用来存储 FFT 的交叉顺序,所以应该是整数类型。
用 ZFFTI 获得值以后,可以供 ZFFTF 和 ZFFTB 使用。所以你只要把他们都定义为 integer 即可。 |
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