void cross_corr(int n, real f[], real g[], real corr[])
{
gmx_fft_t fft;
gmx_fft_init_1d(&fft, zeroPaddingSize(n), GMX_FFT_FLAG_CONSERVATIVE);
cross_corr_low( n, f, g, corr, fft);
gmx_fft_destroy(fft);
gmx_fft_cleanup();
}
/*! \brief
* Compute one cross correlation corr = f x g using FFT.
*
* \param[in] n number of data point
* \param[in] f first function
* \param[in] g second function
* \param[out] corr output correlation
* \param[in] fft FFT data structure
*/
static void cross_corr_low(int n, real f[], real g[], real corr[], gmx_fft_t fft)
{
int i;
const int size = zeroPaddingSize(n);
double ** in1, ** in2;
snew(in1, size);
snew(in2, size);
for (i = 0; i < size; i++)
{
snew(in1[i], 2);
snew(in2[i], 2);
}
for (i = 0; i < n; i++)
{
in1[i][0] = (double)f[i];
in1[i][1] = 0;
in2[i][0] = (double)g[i];
in2[i][1] = 0;
}
for (; i < size; i++)
{
in1[i][0] = 0;
in1[i][1] = 0;
in2[i][0] = 0;
in2[i][1] = 0;
}
gmx_fft_1d(fft, GMX_FFT_FORWARD, in1, in1);
gmx_fft_1d(fft, GMX_FFT_FORWARD, in2, in2);
for (i = 0; i < size; i++)
{
complexConjugatMult(in1[i], in2[i]);
in1[i][0] /= size;
}
gmx_fft_1d(fft, GMX_FFT_BACKWARD, in1, in1);
for (i = 0; i < n; i++)
{
corr[i] = (real)(in1[i][0]);
}
for (i = 0; i < size; i++)
{
sfree(in1[i]);
sfree(in2[i]);
}
sfree(in1);
sfree(in2);
}
void many_cross_corr(int nFunc, int * nData, real ** f, real ** g, real ** corr)
{
#pragma omp parallel
//gmx_fft_t is not thread safe, so structure are allocated per thread.
{
int i;
#pragma omp for
for (i = 0; i < nFunc; i++)
{
gmx_fft_t fft;
gmx_fft_init_1d(&fft, zeroPaddingSize(nData[i]), GMX_FFT_FLAG_CONSERVATIVE);
cross_corr_low( nData[i], f[i], g[i], corr[i], fft);
gmx_fft_destroy(fft);
}
}
gmx_fft_cleanup();
}
/*! \brief
* Compute one cross correlation corr = f x g using FFT.
*
* \param[in] n number of data point
* \param[in] f first function
* \param[in] g second function
* \param[out] corr output correlation
* \param[in] fft FFT data structure
*/
static void cross_corr_low(int n, const real f[], const real g[], real corr[], gmx_fft_t fft)
{
int i;
const int size = zeroPaddingSize(n);
t_complex * in1, * in2;
snew(in1, size);
snew(in2, size);
for (i = 0; i < n; i++)
{
in1[i].re = f[i];
in1[i].im = 0;
in2[i].re = g[i];
in2[i].im = 0;
}
for (; i < size; i++)
{
in1[i].re = 0;
in1[i].im = 0;
in2[i].re = 0;
in2[i].im = 0;
}
gmx_fft_1d(fft, GMX_FFT_FORWARD, in1, in1);
gmx_fft_1d(fft, GMX_FFT_FORWARD, in2, in2);
for (i = 0; i < size; i++)
{
complexConjugatMult(&in1[i], &in2[i]);
in1[i].re /= size;
}
gmx_fft_1d(fft, GMX_FFT_BACKWARD, in1, in1);
for (i = 0; i < n; i++)
{
corr[i] = in1[i].re;
}
sfree(in1);
sfree(in2);
}
