I'm very new to matlab and need some help finding the correct syntax to do a simple data graphing task. I have a script that analyzes a wave form and saves a six point vector (its value is <3791x6 double>) called features. I need to go through the values in the fifth data space, record whether or not they are above a certain threshold, then graph the results (time vs. above/below threshold). 

Here is the basic pseudo code. What is the proper Matlab syntax?

```
create a time vs. boolean vector 'threshold'
fifth column of 'features' equals new vector 'data'
for each value in 'data'
     if (data[index] > threshold value) threshold[index] = true
     else threshold[index] = false
graph(threshold)

```