finding intersection point between a scatter and vertical lines

Is there any way to find the y values of the intersection points between a scatter and vertical lines?

[Vaultec]

If possible, Im looking for something that wont require the file exchange, as my script will need to work on multiple copies of matlab

Answer 1

[Star Strider]

Use interp1. I had to do a fair amount of coding to get the data from your figure, but since you will have all the original data, you can skip directly to the YIsx = interp1 step:

openfig('figure 10.fig');               % Get figure & extract data
h1c = get(gca, 'Children');
Xdc = get(h1c, 'XData');
DSz = cellfun(@max,(cellfun(@size, Xdc, 'Uni',0))); % Get data sizes
IdxMx = find(DSz == max(DSz));
Xdmx = cell2mat(Xdc(IdxMx));
Xd = cell2mat(Xdc(setdiff(1:length(Xdc),IdxMx)));   % X-values of vertical lines
Ydc = get(h1c, 'YData');
Ydmx = cell2mat(Ydc(IdxMx));
% Yd = cell2mat(Ydc);

YIsx = interp1(Xdmx, Ydmx, Xd(:,1));    % Find intersections

hold on
plot(Xd(:,1), YIsx, '+r', 'MarkerSize',10, 'LineWidth',2)   % Plot intersections
hold off

produces:

Answer 2

[Ben11]

You might want to use this submission from File Exchange:

http://www.mathworks.com/matlabcentral/fileexchange/11837-fast-and-robust-curve-intersections

I never tried it myself but it looks great.