Functions  
void  difference_of_gaussians (const Support::buffer_type &F, const float center_wave_length, Support::buffer_type *const G, Support &support) 
void  difference_of_gaussians (const Support::buffer_type &F, const float small_wave_length, const float large_wave_length, Support::buffer_type *const G, Support &support) 
Duplication of the mix function to avoid back and forth copy from buffer. 

Duplication of the mix function to avoid back and forth copy from buffer. This function works only in fourier domain. Filter f by (Gassian_small  Gaussian_large). f is given through its Fourier transform F in a Support::buffer_type. g is given back through its Fourier transform G in a Support::buffer_type. 

Filter f (represented by its Fourier transform) by a passband filter centered on 