Intersecti​on of line and curve

Question

I want the opinion of others as to the best way to approach this situation.
I have a curve defined by (x,y1), and also a straight line y2 = constant. In the example below, y2 = 2.
I want to find the intersection of the curve with the line.
My apporach is as follow:
1. Find the polynomial coefficients of the curve(x,y1) using general polynomial fit
2. subract (y2 = 2) from  the first polynomial coeficient i.e solving y1 = y2
3. Solve the equation of the polynomial equation using polynomial roots
I want to see if there are other ideas.
Thanks.

Answer 1

Blueyes,
Your code misses one of the two intersections. The Insert into Array overwrites the first intersection with the second one.  Build Array is a better choice.  If the number of intersections could be large, pre-initializing the array and using Replace Array Subset is the best choice.
You can simplify things a bit by using autoindexing.  No need for the Array length.  Use of a shift register eliminates the Y1 Index Array and autoindexing eliminates the X Index Array. Wiring Y2 constant value directly to the In Range and Coerce functions eliminated the need to index the Y2 array, which is only needed for the plot.
If the Y1 array has noise or horizontal sections, other techniques may need to be used.
Lynn
Attachments:
IntersectionExample_LV2009.2.vi ‏22 KB