How to find the last position in an array where a value is met

I have an array of about 100 elements, all random generated by a function and I need to find the last position where the value 0.98 is met. Also, the values are with more than 6 decimals so they need to be approximated to just 2, but I can do that with round function.

Ox axis is an array that contains time values, and Oy axis is an array which contains the values of the function. I have to find the last value on Oy where y (the function) is + or - 2% of 1 (which is 0.98 or 1.02).

Answer 1

[Walter Roberson]

find(y >= 0.98, 1, 'last')

Or for your expanded requirement,

find(y >= 0.98 & y <= 1.02, 1, 'last')

[Robert Marasescu]

My numbers in y array are like these

so it will never find the right value. Also i've tried

find(round(y,2,'significant') >= 0.98 & round(y,2,'significant') <= 1.02, 1, 'last');

but it gives me the index 101, which is the last one.

find(y >= 0.98 & y <= 1.02, 1, 'last')

also gives me index 101;

[Walter Roberson]

What is the value of y(end) ? If the plot you included represents the data, then the value at the right hand side is between 0.98 and 1.02: visually we can see that the value is quite close to 1.0

[Tanner DeKruyter]

I know this is a bit late, but I'm in controls right now and just did this. You need to reverse the bounds to search outside the 2% from steady state. My code was instead:

ts_idx = find(or(y1 <= 0.98*yss, y1 >= 1.02*yss), 1, 'last');