fft_structure_function.c

/**
 * @file    fft_structure_function.c
 * @brief   Compute structure function using FFT
 *
 *
 */

#include <math.h>

#include "CommandLineInterface/CLIcore.h"

#include "COREMOD_memory/COREMOD_memory.h"

#include "fft_autocorrelation.h"

imageID fft_structure_function(const char *ID_in, const char *ID_out)
{
    imageID  IDout;
    double   value;
    uint64_t nelement;
    uint8_t  datatype;

    autocorrelation(ID_in, ID_out);
    IDout    = image_ID(ID_out);
    nelement = data.image[IDout].md[0].nelement;

    datatype = data.image[IDout].md[0].datatype;

    if(datatype == _DATATYPE_FLOAT)
    {
        value = -data.image[IDout].array.F[0];
        for(uint64_t ii = 0; ii < nelement; ii++)
        {
            data.image[IDout].array.F[ii] += value;
            data.image[IDout].array.F[ii] *= -2.0 / sqrt(nelement);
        }
    }
    if(datatype == _DATATYPE_DOUBLE)
    {
        value = -data.image[IDout].array.D[0];
        for(uint64_t ii = 0; ii < nelement; ii++)
        {
            data.image[IDout].array.D[ii] += value;
            data.image[IDout].array.D[ii] *= -2.0 / sqrt(nelement);
        }
    }

    return IDout;
}