Name

sfft_init_2d, dfft_init_2d, cfft_init_2d, zfft_init_2d − Initialization step for fast fourier transform in two dimensions

FORMAT

status = {S,D,C,Z}FFT_INIT_2D (ni, nj, fft_struct, ni_stride_1_flag)

Arguments

ni, njinteger∗4
Specifies the size of the first and second dimension of data in the input array; ni > 0, nj > 0. For SFFT_INIT_2D and DFFT_INIT_2D, ni must be even. 

fft_structrecord /dxml$s_fft_structure_2d/ for single-precision real operations
record /dxml$d_fft_structure_2d/ for double-precision real operations
record /dxml$c_fft_structure_2d/ for single-precision complex operations
record /dxml$z_fft_structure_2d/ for double-precision complex operations
This argument must be included but needs no additional definitions. The argument is declared in the program before this routine. See <REFERENCE>(fft_struct_sec) for more information.

ni_stride_1_flaglogical
Specifies whether to allow a stride of more than 1 between elements in the row:

TRUE: Stride must be 1. 

FALSE: Stride is at least 1. 

Description

The _FFT_INIT_2D functions build internal data structures needed to compute fast Fourier transforms of two-dimensional data.  These routines are the first step in a three-step procedure.  They create the internal data structures, using attributes defined in the file DXMLDEF.FOR. 

Use the initialization routine that is appropriate for the data format.  Then, use the corresponding application and exit steps to complete the procedure. For example, use the SFFT_2D_INIT routine with the SFFT_2D_APPLY and SFFT_2D_EXIT routine. 

Return Values

0DXML$_SUCCESS()

4 (real transform only)
DXML$_ILL_N_IS_ODD()

8DXML$_ILL_N_RANGE()

12DXML$_INS_RES()