Hi,
I looked into the extra suggestions.
Getting more confused as my knowledge in this, is way below the things you guys offer.
Willing to learn so I started with the Excel option to see the proposed curves.
Now here again some expect one to build things as easy as it sounds. 
I can create collums and graphs in Excel but putting the fourmula and copy them to the cells is the tricky part.
I have done it manually but know this could be performed automaticly.
Probably used the wrong formula.
Paco
formula y=squareb.xlsx (14.2 KB)