— Function: int gsl_histogram2d_memcpy (gsl_histogram2d * dest, const gsl_histogram2d * src)

This function copies the histogram src into the pre-existing histogram dest, making dest into an exact copy of src. The two histograms must be of the same size.

— Function: gsl_histogram2d * gsl_histogram2d_clone (const gsl_histogram2d * src)

This function returns a pointer to a newly created histogram which is an exact copy of the histogram src.