Thank you for the links, and the Excel example.

It seems that what I need now is to find out how LINEST is calculated. Once I get the 3 numbers (a & b & c), I can draw the Polinomial Regression.

I looked up on the internet and I can't find anything, I have to code it in Visual Basic, and also in C/C++

In Visual Basic, I can create an Excel object, and just call the LinEst function, but if i do it in C++, I can't, I have to re-invent the wheel, and actually create the LinEst function.

Do you know how LINEST is calculated ?

Thanks