Point of intersection of two curves

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Wed, 06/13/2012 - 04:46 pm

Hi,

I have two different curves fit by two differrent double exponential functions (in Igor). I am trying to calculate the coordinates of the point of intersection. Is there a fairly simple way to do this in Igor? I've tried to calculate it algebraically, but get into a terrible mess! Many thanks.
Option 1: Use the 'FindLevel' operation on a wave that is the difference of your two waves. The waves must have the same scaling; if they don't you will have to create an Interpolated version of one of them that has the same 'x' scaling as the other. Since you are creating fits to the two original waves, they apparently have noise or deviations so this method may not be appropriate for the original waves. However, if your fitting waves have the same scaling this method should work using them.

Option 2: Use the 'FindRoots' operation on a function constructed from the difference of the two analytic forms of the fitting functions with your best-fit coefficients.

See the Help files or Manual for detailed descriptions of the above operations.

June 14, 2012 at 05:57 am - Permalink

Excellent. I used the 'FindLevel' method on a wave that is the difference of the two waves and it works exactly as I wanted. Many thanks.

June 14, 2012 at 08:12 am - Permalink