You might think that calculating intersection points is pretty trivial but there are complications in computing that you don't get in math

2 straight lines

If you run x=[1 2 3] y1=[ 0 1 2] y2=[2 1 0] plot(x,y1,x,y2) you'll see that the lines cross at x=2, y=1. Using maths we could

Problem 1: precision

Problem 2: precision - close lines

Problem 3: intersection not at a datapoint

x=1:10 y1=sin(x) y2=cos(x) plot(x,y1,x,y2) You'll see that the lines clearly cross twice, but they don't cross at one of the plotted points, so y1-y2 is never 0. We need to interpolate the values, but to do that we need to make assumptions about the nature of the data - should the points ... be connected by straight lines or curves? If curves, what type? In general the data's likely to come from an experiment. If the 2 sets of data don't share the same same of xcoordinates there are further complications.