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Text File  |  1996-03-14  |  4KB  |  133 lines
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  4. ccccfffffffftttt1111ddddiiii,,,,zzzzfffffffftttt1111ddddiiii((((3333FFFF))))                                        ccccfffffffftttt1111ddddiiii,,,,zzzzfffffffftttt1111ddddiiii((((3333FFFF))))
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  8. NNNNAAAAMMMMEEEE
  9.      ccccfffffffftttt1111ddddiiii,,,, zzzzfffffffftttt1111ddddiiii ---- initialize the coefficient array for Complex-to-
  10.      Complex 1D FFT modules.
  11.  
  12. SSSSYYYYNNNNOOOOPPPPSSSSYYYYSSSS
  13.      _F_O_R_T_R_A_N _S_P_E_C_I_F_I_C_A_T_I_O_N subroutine CFFT1DI( n, coeff )
  14.      iiiinnnntttteeeeggggeeeerrrr             nnnn
  15.      ccccoooommmmpppplllleeeexxxx             ccccooooeeeeffffffff((((nnnn++++11115555))))
  16.  
  17.      ssssuuuubbbbrrrroooouuuuttttiiiinnnneeee ZZZZFFFFFFFFTTTT1111DDDDIIII(((( nnnn,,,, ccccooooeeeeffffffff ))))
  18.      iiiinnnntttteeeeggggeeeerrrr             nnnn
  19.      ddddoooouuuubbbblllleeee ccccoooommmmpppplllleeeexxxx      ccccooooeeeeffffffff((((nnnn++++11115555))))
  20.  
  21.      _C _S_P_E_C_I_F_I_C_A_T_I_O_N
  22.      ####iiiinnnncccclllluuuuddddeeee <<<<fffffffftttt....hhhh>>>>
  23.      ccccoooommmmpppplllleeeexxxx ****ccccfffffffftttt1111ddddiiii(((( iiiinnnntttt nnnn,,,, ccccoooommmmpppplllleeeexxxx ****ccccooooeeeeffffffff))));;;;
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  25.      zzzzoooommmmpppplllleeeexxxx ****zzzzfffffffftttt1111ddddiiii(((( iiiinnnntttt nnnn,,,, zzzzoooommmmpppplllleeeexxxx ****ccccooooeeeeffffffff))));;;;
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  28. DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  29.      Initialize the coefficient array which is used in the FFT modules.  This
  30.      array contains the different twiddle factors and the factorization of N
  31.      into prime numbers.
  32.      As the FFT modules cfft1d or zfft1d only read the _c_o_e_f_f array, it may be
  33.      reused as long as necessary once it has been initialized.
  34.  
  35.      In C, if _p_t_r is NULL, _c_f_f_t_1_d_i or _z_f_f_t_1_d_i returns a pointer to an
  36.      allocated buffer.
  37.  
  38.      CFFT1DI should be used to initialize the coeeficient array before any
  39.      call to CFFT1D
  40.      ZFFT1DI should be used to initialize the coeeficient array before any
  41.      call to ZFFT1D
  42.  
  43. PPPPAAAARRRRAAAAMMMMEEEETTTTEEEERRRRSSSS
  44.      NNNN ---- Integer. Specifies the length of the sequence to be transformed.
  45.      Unchanged on exit.
  46.  
  47.      CCCCOOOOEEEEFFFFFFFF ---- Array (C or Fortran) or NULL pointer(C).
  48.  
  49. EEEExxxxaaaammmmpppplllleeee ooooffff CCCCaaaalllllllliiiinnnngggg SSSSeeeeqqqquuuueeeennnncccceeee
  50.      Initializing a coefficient array for complex-to-complex FFTs of size 200.
  51.  
  52.      _F_o_r_t_r_a_n :
  53.           complex coeff(200+15)
  54.           call cfft1di( 200, coeff)
  55.  
  56.      _C :
  57.           #include <fft.h>
  58.           float *coeff;
  59.           coeff = cfft1di( 200, NULL);
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  63.                                                                         PPPPaaaaggggeeee 1111
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  70. ccccfffffffftttt1111ddddiiii,,,,zzzzfffffffftttt1111ddddiiii((((3333FFFF))))                                        ccccfffffffftttt1111ddddiiii,,,,zzzzfffffffftttt1111ddddiiii((((3333FFFF))))
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  74. SSSSEEEEEEEE AAAALLLLSSSSOOOO
  75.           fft, cfft1d, zfft1d
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  129.                                                                         PPPPaaaaggggeeee 2222
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