How to input two values as one value

Hi, I'm wondering how two different values can be combined into one individual value. For example, I have a signal Y with 10000 samples, with 100 samples equalling to 1 second. If I were trying to plot Y in terms of seconds, that is rather easy to do by using a code

samples = length(Y);
fs = 100;
time = 0:1/fs:samples/fs-1/fs;

and then simply plotting plot(time, Y). However, If I wanted to do something like plotting the power spectrum density of the signal using pwelch but only for the section between 20 and 40 seconds, how would I code this? Thanks

Answer 1

[KSSV]

samples = length(Y);
fs = 100;
time = 0:1/fs:samples/fs-1/fs;
iwant = Y(time>=20 & time<=40))   %<-- this pciks Y for time between 20 and 40 seconds 

[Anthony Koning]

And in this case, to take the pwelch, you would simply define pwelch(iwant), correct?

[KSSV]

Yes.