A thresholded array is an array which has had a threshold applied to it. It
has an attribute thresh which is the threshold that was applied which can
be a number or an object of class th.
threshed_arr(arr, thresh)The thresholded array (not the original array).
The threshold that was used. Either a number or an object of class th.
An object of class threshed_arr.
The term 'array' is used loosely here in that vectors and matrices qualify as arrays.