Can a line equation be altered?

I have a smooth line, XY scatter chart using a cubic spline equation, the problem is that the cubic spline equation produces negative values when plunging to zero. When graphed, this causes people to wonder “how do you get a negative number of widgets”, or the graphline vanishes and reappears as it goes microscopically above and below zero.

Is there a way to either “override” the cubic spline equation with my own (identical, except with a `if y<0 then y=0`

line), or to create my own equation along the lines of:

```
M_Bison_Cubic_Spline(passedinfo)
y=LO_Cubic_Spline(passedinfo)
if y<0 then y=0
M_Bison_Cubic_Spline=y
End function
```

Then how would I tell my `ochart=blah.Charts(0)`

to use my custom equation? Am I completely off-base here? I know I’m mixing and mangling terminology, let me know if I can help clarify this.

Lastly, everyone keeps saying “you get what you pay for” and stuff like that… It’s B.S. Your software and support has been invaluable (this is my first question that I couldn’t find the answer to), so thank you.