odd shaped chart area envelope, how do I flag a plot falls outside the area?

[jetclub1]

i have a graph, actually it is an aircraft weight and balance chart. It has an odd shaped envelope. How do I create a warning if a plot falls outside this area? If the area was square it would be easy with =IF(and(j23<23%,j24>4000),"warning","ok")) etc etc. but what if the area is an odd shape where on one side x increase and y decreases, on the other it is the other way.
Any ideas? so basically I want to create a warning flag when the plot falls outside the designated area.
Am I getting too complicated here?

Thank you

 

[jetclub1]

Ok, as I thought too complex for me.

I would really like to understand how to do this but i do not. I see the idea but don't know where to start sorry.

 

[shg]

Well within the capabilities of jet pilot.

Add the code to a code module, then use the function as in the example.

Adding a Macro to a Code Module<?xml:namespace prefix = o ns = "urn:schemas-microsoft-comfficeffice" /><o></o>
1. Copy the code from the post<o></o>
2. Press Alt+F11 to open the Visual Basic Editor (VBE)<o></o>
3. From the menu bar in the VBE window, do Insert > Module<o></o>
4. Paste the code in the window that opens<o></o>
5. Press Alt+Q to close the VBE and return to Excel<o></o>

If you have problems (but you shouldn't), I'll post a link to a workbook with the function in it.

 

[jetclub1]

i will try, thanks