Ciao FrancescoCiao , how much memory does your machine have? with 2.2.3 if z+0j and z+1j works fine, while z+2j does not, it may well be a memory problem (plus the ‘Cannot allocate memory’ error). Can you monitor the RAM usage when one generates z+2j merged sample and let me know how much of it is used? Ciao, Marco On 26 Jan 2015, at 19:54, Francesco Giuli