Ahh, the actual difficulty in your problem rears it's ugly head.
/methinks this may be beyond what a VB program can handle. I'd guess that you'd need the computing power of
Maple(my personal fav - Yeah Canada!) or
Matlab. BTW, you're still looking at a few thousand bucks for these programs...
And in case I haven't already crushed your spirits, here's a taste of what spline theory is about
:
Cubic Spline Interpolation
This approach will approximate your curve with a spline function, from which some high-powered math can solve for such things as area.
Maybe something simpler in VB will give a close enough approximation.
Let us know how you get on with it!