Hey all,

I am a beginning macros user and I would like to do the following:
Assume I have this matrix (the 1st row A is an increasing parameter, the values of the 2nd row B are decreasing until a minimum several times)

A 2 4 6 8 10 12 14 16 18 20
B 8 5 4 2 -1 2 1 -4 -5 -7

I want to make a macro that does the following:
1) Find each first negative value of the 2nd row and perform an interpolation to find the A-value corresponding to the zero points (2 in this case) from row B.
--> for example here the program should find 2 and -1; but also 1 and -4. The corresponding "zero point values of A" would be 9.333 and 14.400.

Can somebody help me out here? The interpolation formula is not needed, i just want to know how i can make this run in a loop.

Thank you guys in advance!

Best,
Arnaud