Hi Kevin,
If you just want to compute/print out the x value for the intersection (and not necessarily want it as part of the fit report), you could use a script solution such as below:
First plot your data and use the Regional Data Selector tool from the Tools menu to select/mark two ranges on your data.
Then run the following script:
nlbegin func:=line nlt:=mytree;
nlfit;
nlend 1;
double a1,b1,a2,b2;
a1=mytree.a;
b1=mytree.b;
a2=mytree.a_2;
b2=mytree.b_2;
double myx=(a2-a1)/(b1-b2);
type "The two lines intersect at x=$(myx)";
You can look up documentation on nlfit, nlend etc in the LT Guide for version 8.1 in the product, or from this wiki area:
http://wiki.originlab.com/~originla/wiki/index.php?title=Category:LabTalk_Programming
Also once a fit has been done, there is a getnlr X-function that can be used to programmatically get all information from a report sheet.
Easwar
OriginLab