When Y = 0.5, what is X

Hello!

I have a scatter plot but I want to find a way for MatLab to give me the value of X when Y=0.5 in the command window, how would I do this?

Answer 1

[Image Analyst]

You didn't attach your data, probably because you haven't yet read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

but you can find the index where Y is that value, then use that index in X to get the X value.

index = find(Y == 0.5)
output = X(index);

If y is not exactly that (a power of 2) then you'll have to use min():

% Get sample data.
X = sort(rand(1, 100));
Y = rand(1, 100);
% Plot it.
plot(X, Y, 'b.', 'MarkerSize', 30);
grid on;
yline(0.5, 'LineWidth', 2)
% Find out which point is closest to Y = 0.5.
differenceValues = abs(Y - 0.5);
[~, index] = min(differenceValues)
outputX = X(index);
outputY = Y(index);
% Plot it.
hold on;
plot(outputX, outputY, 'ro', 'MarkerSize', 30, 'LineWidth', 2)