On Fri, 31 Jul 2009 23:30:50 -0700 (PDT), Harish
wrote:

Hi,

I have two curves plotted in excel using the data points and these two
curves intersect. I want to find the intersection coordinates of these
2 curves. How do I do that? Thanks in advance

Swamy

Assuming that your X-data are in cells A1:A10 and your Y-data are in
cells B1:B10 for the first curve and in C1:C10 for the second curve.

Try this formulas to find the coordinates for the first intersection.

For the X-coordinate:

=INDEX(A1:A10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)+
(INDEX(A1:A10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0)))-
INDEX(A1:A10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1))*
(INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)-
INDEX(C1:C10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1))/
(INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)-
INDEX(C1:C10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)-
INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0)))+
INDEX(C1:C10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))))

For the Y-coordinate:

=INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)+
(INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0)))-
INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1))*
(INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)-
INDEX(C1:C10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1))/
(INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)-
INDEX(C1:C10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))-1)-
INDEX(B1:B10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0)))+
INDEX(C1:C10,INDEX(A1:A10,MATCH(-SIGN(B1-C1),SIGN(B1:B10-C1:C10),0))))

Note: These are array formulas that have to be confirmed with
CTRL+SHIFT+ENTER rather than just ENTER

Change the ranges to fit the size of your data.

Hope this helps / Lars-Åke