/**
* C++ version of gsl_fft_real_float_radix2_transform().
* @param data An array of float values.
* @param n The size of the array.
* @return Error code on failure.
*/
inline int transform( float data[], size_t const n ){
return gsl_fft_real_float_radix2_transform( data, 1, n ); }
/* Produce a vector of chisquared values as a function of frequency */
void fastChi(const double *sampletimes, const float *vals, const float *stderrs,
long ndata, long nharmonics, double deltat,
long nrealpoints, long nchivalues, double tstart,
float *dovstorage, float *oovstorage,
float *chireductionlist)
{
int d;
int i;
int h;
float invdeltat = 1/deltat;
gsl_matrix *alpha = gsl_matrix_alloc(2 * nharmonics + 1,2 * nharmonics + 1);
gsl_vector *beta = gsl_vector_alloc(2 * nharmonics + 1);
gsl_vector *x = gsl_vector_alloc(2 * nharmonics + 1);
float *cosdata = malloc((nharmonics + 1) * sizeof(float));
float *sindata = malloc((nharmonics + 1) * sizeof(float));
float *cosvar = malloc((2*nharmonics + 1) * sizeof(float));
float *sinvar = malloc((2*nharmonics + 1) * sizeof(float));
/* if the pointers point somewhere, assume that they point to the right place */
assert(sampletimes && vals && stderrs && dovstorage && oovstorage && chireductionlist);
assert(nchivalues * 2 * nharmonics <= nrealpoints); /* FIXME: change 2 to 1 when */
/* using aliasing */
assert(cosdata && sindata && cosvar && sinvar);
memset(dovstorage, 0, nrealpoints * sizeof(float));
memset(oovstorage, 0, nrealpoints * sizeof(float));
for (d = 0 ; d < ndata ; d++)
{
long tindex = (sampletimes[d] - tstart) * invdeltat;
float inv_variance = 1/(stderrs[d] * stderrs[d]);
assert(tindex >= 0 && tindex < nrealpoints);
/* adding rather than setting averages measurments that */
/* fall in same timebin. It does, however, reduce the d.o.f. */
/* and subsequently improperly reduces the chisquared. */
/* This is a minor point. */
/* dov: _d_ata _o_ver _v_ariance oov: _o_ne _o_ver _v_ariance */
dovstorage[tindex] += vals[d] * inv_variance;
oovstorage[tindex] += inv_variance;
}
gsl_fft_real_float_radix2_transform(dovstorage, 1, nrealpoints);
gsl_fft_real_float_radix2_transform(oovstorage, 1, nrealpoints);
cosdata[0] = dovstorage[0]; /* The constant (0f) terms are the same for all f */
cosvar[0] = oovstorage[0];
for (i = 1 ; i < nchivalues ; i++)
{
for (h = 1 ; h <= nharmonics ; h++)
{
cosdata[h] = dovstorage[i*h];
sindata[h] = dovstorage[nrealpoints - (i * h)] * FFTSIGNCONVENTION;
}
for (h = 1 ; h <= 2*nharmonics ; h++)
{ /* put alias wrapping in here */
cosvar[h] = oovstorage[i*h];
sinvar[h] = oovstorage[nrealpoints - (i * h)] * FFTSIGNCONVENTION;
}
chireductionlist[i]
= calcChiReduction(nharmonics,
cosdata, sindata, cosvar, sinvar,
alpha, beta, x);
}
gsl_matrix_free(alpha);
gsl_vector_free(beta);
gsl_vector_free(x);
free(cosdata);
free(sindata);
free(cosvar);
free(sinvar);
}
inline int transform( DATA& data, size_t const stride = 1 ){
return gsl_fft_real_float_radix2_transform( data.data(), stride, data.size() / stride ); }
