Sory I answer so so late. I haven’t been programming for a long time.
Theoretically it would be possible to programm the polynomial interpolation to as many points as you want. But it gets very complicated.
You need to calculate the coefficients (bi) for as many points as you want for your polynomial function. And you see that the formula for b4 is already very complicated.
I am a very bad programmer (still learning the basics). And I don’t understand the mathematical theory about polynomial interpolation very well. I was quite surprised that my code is working.
So in the near future I won’t expand my polynomial interpolation function to support more then four points. Sory about that.
But maybe you could do it yourself. Just find some informations about Newton polinomial interpolation and expand my function.
Please tell me, if you make some progress.
I don’t know very much about Powerpoint. But for mathematical stuff you shoud use Excel (or a real math program).