when i calculate 1d transform Real-to-Complex of an array of 500 elements
the function returns an array where the first 251 positions are the coefficients and the other 249 are ‘nan’-

this because (i suppose) the transform of a real function is simmetric, so i can calculate the 249 missing elements simply copying
the complex coniugate of the first 250 elements.

here the question:
in which position is the freq 0 in the array that the function returns? 0 or 251?