kml_fft(f)_plan_dft_c2r_2d

Create a plan for the two-dimensional C2R transform of a single contiguous data sequence.

Interface Definition

C interface:

kml_fft_plan kml_fft_plan_dft_c2r_2d(int n0, int n1, kml_fft_complex *in, double *out, unsigned flags);

kml_fftf_plan kml_fftf_plan_dft_c2r_2d(int n0, int n1, kml_fftf_complex *in, float *out, unsigned flags);

Fortran interface:

RES = KML_FFT_PLAN_DFT_C2R_2D( N0, N1, IN, OUT, FLAGS);

RES = KML_FFTF_PLAN_DFT_C2R_2D( N0, N1, IN, OUT, FLAGS);

Return Value

The function returns a structure pointer of the kml_fft(f)_plan type. This object is used as a parameter in the kml_fft(f)_execute function to perform FFT on the current input and output. In addition, the object may also be added into the kml_fft(f)_execute_dft_c2r function as a parameter to perform FFT on the new input and output.

If this function returns a non-null pointer, the plan has been successfully executed. Otherwise, the plan failed to be executed.

Parameters

Parameter	Data Type	Description	Input/Output
n0	int	Inputs the size of the first dimension in the FFT sequence. The constraint is n0 >= 1.	Input
n1	int	Inputs the size of the second dimension in the FFT sequence. The constraint is n1 >= 1.	Input
in	Double precision: kml_fft_complex* Single precision: kml_fftf_complex*	Inputs the data to be transformed.	Input
out	Double precision: double* Single precision: float*	Outputs the data generated using FFT.	Output
flags	unsigned int	A planning option, not in use.	Input

Dependencies

C: "kfft.h"

Fortran: "kfft.f03"

Examples

C interface:

    int n0 = 4; 
    int n1 = 4; 
    double init[12][2] = {{120, 0}, {8, 8}, {0, 0}, {0, 16}, {0, 16}, {-8, 8}, {-8, 0}, {-8, 8}, {-16, 0}, {0, -16}, {-40, 8}, {-8, -8}}; 
    kml_fft_complex *in; 
    in = (kml_fft_complex*)kml_fft_malloc(sizeof(kml_fft_complex) * n0 * (n1 / 2 + 1)); 
    for (int i = 0; i < n0 * (n1 / 2 + 1); i++){ 
        in[i].r = init[i][0]; 
        in[i].i = init[i][1]; 
    } 
    double *out; 
    out = (double*)kml_fft_malloc(sizeof(double) * n0 * n1); 
    kml_fft_plan plan; 
    plan = kml_fft_plan_dft_c2r_2d(n0, n1, in , out , KML_FFT_ESTIMATE);  
    kml_fft_execute_dft_c2r(plan, in, out); 

    kml_fft_destroy_plan(plan); 
    kml_fft_free(in); 
    kml_fft_free(out); 

    /* 
     * out = {0.000000e+00, 6.400000e+01, 1.600000e+02, 2.240000e+02, 
     *        1.120000e+02, 1.600000e+01, 8.000000e+01, 1.760000e+02, 
     *        1.920000e+02, 1.280000e+02, 3.200000e+01, 9.600000e+01, 
     *        2.400000e+02, 2.080000e+02, 1.440000e+02, 4.800000e+01} 
     */

Fortran interface:

    INTEGER(C_INT) :: N0 = 4 
    INTEGER(C_INT) :: N1 = 4 
    REAL(C_DOUBLE), DIMENSION(12, 2) :: INIT 
    TYPE(KML_FFT_COMPLEX), POINTER :: IN 
    REAL(C_DOUBLE), POINTER :: OUT 
    TYPE(C_PTR) :: PIN, POUT 
    INTEGER(C_SIZE_T) :: CSIZE, RSIZE 
    CSIZE = N0 * (N1 / 2 + 1) 
    RSIZE = N0 * N1 
    PIN = KML_FFT_MALLOC(SIZEOF(16 * CSIZE)) 
    POUT = KML_FFT_MALLOC(8 * RSIZE) 
    CALL C_F_POINTER(PIN, IN, SHAPE=[CSIZE]) 
    CALL C_F_POINTER(POUT, OUT, SHAPE=[RSIZE]) 
    DATA INIT/120, 8, 0, 0, 0, -8, -8, -8, -16, 0, -40, -8, 0, 8, 0, 16, 16, 8, 0, 8, 0, 16, 8, -8/ 
    INTEGER :: I 
    DO WHILE(I <= CSIZE) 
        IN(I)%R = INIT(I, 0) 
        IN(I)%I = INIT(I, 1) 
    END DO 
    TYPE(C_PTR) :: PLAN 
    PLAN = KML_FFT_PLAN_DFT_C2R_2D(N0, N1, IN , OUT , KML_FFT_ESTIMATE);  
    CALL KML_FFT_EXECUTE_DFT_C2R(PLAN, IN, OUT); 

    CALL KML_FFT_DESTROY_PLAN(PLAN) 
    CALL KML_FFT_FREE(PIN) 
    CALL KML_FFT_FREE(POUT) 

    ! 
    ! OUT = /0.000000e+00, 6.400000e+01, 1.600000e+02, 2.240000e+02, 
    !        1.120000e+02, 1.600000e+01, 8.000000e+01, 1.760000e+02, 
    !        1.920000e+02, 1.280000e+02, 3.200000e+01, 9.600000e+01, 
    !        2.400000e+02, 2.080000e+02, 1.440000e+02, 4.800000e+01/ 
    !

Parent topic: C2R Transforms