You code is almost right, just the function floating is not known to MATLAB. It doesn't exist, unless you have written it yourself, and using it probably gives you an error ("Undefined function..."). But that is alright, the data class of data{2} values is not really very important anyway, as the < operator is defined for all numeric classes anyway, as well as logical and character arrays. Try this:
idx = data{2} < 121;
sum(~idx)
The documentation states the applicable data types for the lt operator. Tip: Have a look at the "Contents" panel on the left-hand side of the webpage. Explore it for a few minutes: this is a really great way to find related functions, and to explore what you can do with particular classes of data. Get comfortable with using these "Contents" and using MATLAB becomes a lots more fun and interesting!
