Well, unfortunately I don't know any croatian...Only english, german and greek. I am trying to follow your instructions, which is a little bit different from what I was doing until now. Tomorrow I will have some results on how effective it was. I will let you know. One more question, in order for the interpolation to be conservative, what should I do different from usual?

Thank you in advance!

Well, I did not manage to follow the methodology that you advised me to do. Not because the one that I follow is better, but my code takes too much time to be compiled. It is around 15000 lines and I have only a Pentium 3 processor and the compilation takes around half an hour, so any tests that I make should be very-very carefully planned. But I will try tomorrow maybe. Thank you again for your time!