DFT exercise in the book Understanding digital signal processing 3 Ed
@Henrique Luna. Please forgive me. In Part (b) of the problem the words &quot;sequence time&quot; should &quot;time sequence&quot;. Sorry for the confusion!
Years ago when I created that Part (b) question I was thinking about the answer to the question; &quot;What is the time duration of an N-sample time-domain sequence?&quot; Back then I believed the time duration under consideration to be the time difference between the sequence's first and last samples, rather than N times the time interval (1/fs) between the samples. Thinking this way leads to the conclusion that Part (b)'s answer is (N-1)*1/fs = 0.999977 seconds.
But subsequent discussion, years ago, with Dilip Sarwate convinced me that my concluded answer to 3.3 Part (b) may be somewhat valid when thinking about the time-domain but my concluded answer leads to confusion when thinking about signal durations in the context of spectrum analysis.
I now believe the 3.3 Part (b) question leads to more confusion than enlightenment. That Part (b) question was not my most well thought-out homework problem.
By the way Henrique, if you have not done so already, please have a look at the following web page: https://www.dsprelated.com/showarticle/1094.php