kml_fft(f)_plan_r2r_1d

Create a plan for the one-dimensional R2R transform of a single contiguous data sequence.

Interface Definition

C interface:

kml_fft_plan kml_fft_plan_r2r_1d(int n, double *in, double *out, kml_fft_r2r_kind kind, unsigned flags);

kml_fftf_plan kml_fftf_plan_r2r_1d(int n, float *in, float *out, kml_fftf_r2r_kind kind, unsigned flags);

Fortran interface:

RES = KML_FFT_PLAN_R2R_ID(N, IN, OUT, KIND, FLAGS);

KML_FFT_REDFT11 and KML_FFT_ROODFT11 support only sequences whose length is an integer multiple of 4. Other transforms support only sequences whose length is an integer multiple of 2.

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_r2r 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
n	int	Inputs the FFT sequence size. The constraint is n ≥ 1.	Input
in	Double precision: double* Single precision: float*	Inputs the data to be transformed.	Input
out	Double precision: double* Single precision: float*	Outputs the data generated using FFT.	Output
kind	Double precision: kml_fft_r2r_kind Single precision: kml_fftf_r2r_kind	kind indicates the R2R transform type of an FFT sequence. It has the following options: KML_FFT_R2HC KML_FFT_HC2R KML_FFT_DHT KML_FFT_REDFT00 KML_FFT_REDFT01 KML_FFT_REDFT10 KML_FFT_REDFT11 KML_FFT_RODFT00 KML_FFT_RODFT01 KML_FFT_RODFT10 KML_FFT_RODFT11	Input
flags	unsigned int	A planning option, not in use.	Input

Dependencies

C: "kfft.h"

Fortran: "kfft.f03"

Examples

C interface:

    int N = 16; 
    double *in; 
    double *out; 
    kml_fft_plan plan; 
    in = (double*)kml_fft_malloc(sizeof(double) * N); 
    out = (double*)kml_fft_malloc(sizeof(double) * N); 
    for (int i = 0; i < N; i++){ 
        in[i] = (double)i; 
    } 
 
    plan = kml_fft_plan_r2r_1d(N, in , out, KML_FFT_REDFT10, KML_FFT_ESTIMATE); 
    kml_fft_execute_r2r(plan, in, out); 
 
    kml_fft_destroy_plan(plan); 
    kml_fft_free(in); 
    kml_fft_free(out); 
 
    /* 
     * out = {2.400000e+02, -1.035857e+02, 0.000000e+00, -1.135629e+01, 
     *        0.000000e+00, -3.968777e+00, 0.000000e+00, -1.920738e+00, 
     *        0.000000e+00, -1.061666e+00, 0.000000e+00, -6.060758e-01, 
     *        0.000000e+00, -3.169964e-01, 0.000000e+00, -9.896796e-02} 
     */

Fortran interface:

    INTEGER(C_INT) :: N = 16 
    REAL(C_DOUBLE) :: INIT(16) 
    REAL(C_DOUBLE), POINTER :: IN(:), OUT(:) 
    TYPE(C_PTR) :: PIN, POUT 
    INTEGER(C_SIZE_T) :: SIZE 
    SIZE = N 
    DATA KIND/KML_FFT_DHT, KML_FFT_DHT/ 
    PIN = KML_FFT_MALLOC(8 * SIZE) 
    POUT = KML_FFT_MALLOC(8 * SIZE) 
    CALL C_F_POINTER(PIN, IN, SHAPE=[SIZE]) 
    CALL C_F_POINTER(POUT, OUT, SHAPE=[SIZE]) 
    DATA INIT/1, 2, 3, 4, 5, 6, 7, 8/ 
    INTEGER :: I 
    DO WHILE(I <=  SIZE) 
        IN(I) = INIT(I) 
    END DO 
    TYPE(C_PTR) :: PLAN 
    PLAN = KML_FFT_PLAN_R2R_1D(N, IN , OUT, KML_FFT_REDFT10, KML_FFT_ESTIMATE) 
    CALL KML_FFT_EXECUTE_R2R(PLAN, IN, OUT) 
 
    CALL KML_FFT_DESTROY_PLAN(PLAN) 
    CALL KML_FFT_FREE(PIN) 
    CALL KML_FFT_FREE(POUT) 
    ! 
    ! OUT = /2.400000E+02, -1.035857E+02, 0.000000E+00, -1.135629E+01, 
    !        0.000000E+00, -3.968777E+00, 0.000000E+00, -1.920738E+00, 
    !        0.000000E+00, -1.061666E+00, 0.000000E+00, -6.060758E-01, 
    !        0.000000E+00, -3.169964E-01, 0.000000E+00, -9.896796E-02/ 
    !

Parent topic: R2R Transforms