Real transform: status = {S,D}FFT_3D (input_format, output_format, direction, in, out, ni, nj, nk, lda_i, lda_j, ni_stride, nj_stride, nk_stride) Complex transforms in complex format: status = {C,Z}FFT_3D (input_format, output_format, direction, in, out, ni, nj, nk, lda_i, lda_j, ni_stride, nj_stride, nk_stride) Complex transform in real data format: status = {C,Z}FFT_3D (input_format, output_format, direction, in_real, in_imag, out_real, out_imag, ni, nj, nk, lda_i, lda_j, ni_stride, nj_stride, nk_stride)
input_format, output_format character*(*) Identifies the data type of the input and the format to be used to store the data, regardless of the data type. For example, a complex sequence can be stored in real format. The character 'R' specifies the format as real; the character 'C' specifies the format as complex. As convenient, use either upper- or lowercase characters, and either spell out or abbreviate the word. The following table shows the valid values: Subprogram Input Format Output Format Direction {S,D} 'R' 'C' 'F' 'C' 'R' 'B' 'R' 'R' 'F' or 'B' {C,Z} 'R' 'R' 'F' or 'B' 'C' 'C' 'F' or 'B' For complex data, the type of data determines what other arguments are needed. When both the input and output data are real, the complex routines store the data as separate arrays for imaginary and real data so additional arguments are needed. direction character*(*) Specifies the operation as either the forward or inverse transform. Use 'F' or 'f' to specify the forward transform. Use 'B' or 'b' to specify the inverse transform. in, out real*4 | real*8 | complex*8 | complex*16 Both the arguments are three-dimensional arrays. The input and output arrays can be the same array. The IN array contains the data to be transformed. The OUT array contains the transformed data. in_real, out_real, in_imag, out_imag REAL*4 | REAL*8 Use these arguments when performing a complex transform on real data format and storing the result in a real data format. ni, nj, nk integer*4 Specifies the size of the first, second, and third dimension of data in the input array; ni > 0, nj > 0, nk > 0. For SFFT_3D and DFFT_3D, ni must be even. lda_i, lda_j integer*4 Specifies the number of rows and columns in the IN and OUT arrays; lda_i >= ni, lda_j >= nj. For {S,D} routines, lda_i >= ni+2 when the input format is 'R' and the output format is 'C' or the input format is 'C' and the output format 'R'. ni_stride, nj_stride, nk_stride integer*4 Specifies the distance between consecutive elements in the IN and OUT arrays; ni_stride >= 1, nj_stride >= 1, nk_stride >= 1.
The _FFT_3D routines compute the fast forward or inverse Fourier transform of three-dimensional data in one step. The SFFT_3D and DFFT_3D functions perform the forward Fourier transform of a real sequence and store the result in either real or complex data format. These functions also perform the inverse Fourier transform of a complex sequence into a real sequence. The CFFT_3D and ZFFT_3D functions perform Fourier transforms on a complex sequence. However, the argument list is different, depending on the data format in which the output data is stored. See the CXML Reference Manual's chapter on "Using the Signal Processing Subprograms" for an explanation of real and complex data format.
0 DXML_SUCCESS() 4 (with real transforms only) DXML_ILL_N_IS_ODD() 8 DXML_ILL_N_RANGE() 11 DXML_ILL_LDA() 12 DXML_INS_RES() 13 DXML_BAD_STRIDE() 15 DXML_BAD_DIRECTION_STRING() 16 DXML_BAD_FORMAT_STRING() 18 DXML_BAD_FORMAT_FOR_DIRECTION()
INCLUDE 'CXMLDEF.FOR' INTEGER*4 N_I, N_J, N_K, STATUS, LDA_I, LDA_J REAL*8 A(130,128,128), B(130,128,128) N_I = 128 N_J = 128 N_K = 128 LDA_I = 130 LDA_J = 128 STATUS = DFFT_3D('R','C','F',A,B,N_I,N_J,N_K,LDA_I,LDA_J,1,1,1) This FORTRAN code computes the forward, three-dimensional, real FFT of a 128x128x128 matrix A. The result of the transform is stored in B in complex form. Note that the leading dimension of B is 130 to hold the extra complex values (see section on data storage). Note also that the input matrix A requires a leading dimension of at least 130. INCLUDE 'CXMLDEF.FOR' INTEGER*4 N_I, N_J, N_K, STATUS, LDA_I, LDA_J COMPLEX*8 A(128,128,128), B(128,128,128) N_I = 128 N_J = 128 N_K = 128 LDA_I = 128 LDA_J = 128 STATUS = CFFT_3D('C','C','F',A,B,N_I,N_J,N_K,LDA_I,LDA_J,1,1,1) This FORTRAN code computes the forward, three-dimensional, complex FFT of a matrix A, of dimension 128 by 128 by 128. The result of the transform is stored in B in complex form.