MATLAB: Intersection of lines and curves

interpolationintersectionMATLAB

i have data in which line is plotted on a signal having pulses. I want to find out all points of intersections between the line and the curve. Right now i am able to get single point of intersection on only one side of pulse. I also need point of intersection on the other side.

Best Answer

Try this: 
D = load('intersect1.mat');
x_curve = D.x_curve;
y_curve = D.y_curve;
x_line  = D.x_line;
y_line  = D.y_line;
x_curve(x_curve == 0) = [];                                             % Eliminate Spurious Points

y_curve(y_curve == 0) = [];                                             % Eliminate Spurious Points
zci = @(v) find(v(:).*circshift(v(:), -1, 1) <= 0);                     % Returns Approximate Zero-Crossing Indices Of Argument Vector (>= R2016b)
icix = zci(y_curve - y_line(1:end-2));
figure
plot(x_curve, y_curve,    x_line, y_line)
hold on
plot(x_curve(icix), y_curve(icix), 'dr')
hold off
grid
producing:
The x-values of the intersections are about 0.135 and 0.149. (They are: x_curve(icix).)
The points are dense enough that it is not necessary to interpolate them to get reasonably precise values for the intersections.
.
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