In a array, finding x for the first instance of y.

I have a 2d array where x is time and y is result. I am trying to find the first time when y==1.

Answer 1

[Star Strider]

Depending on what you want:

idx = find(y>=1, 1, 'first');
time = x(idx);

or:

idx = find(y>=1, 1, 'first');
time = interp1(y(idx-2:idx), x(idx-2:idx), 1);

The interpolation works if ‘y’ is not exactly equal to 1 and you want to know what that interpolated time would be.

Choose the approach that works best in the context of your problem.