Understanding the following step in MATLAB

2 visualizzazioni (ultimi 30 giorni)
charu shree il 5 Lug 2023
Commentato: charu shree il 5 Lug 2023
Hello all, I came across the following code on MATLAB but not getting its last step:
symbols = randi([0 3], 1, 256);
constellation = [1+1i, -1+1i, -1-1i, 1-1i];
signal = constellation(symbols + 1); % Last step
My query is why " symbols +1 " is written in last step and why not only " symbols".
Any help in this regard will be highly appreciated.
0 CommentiMostra -2 commenti meno recentiNascondi -2 commenti meno recenti

Accedi per commentare.

Risposta accettata

the cyclist il 5 Lug 2023
The line
symbols = randi([0 3], 1, 256)
generates random values from the values [0 1 2 3]. Those zero values are not a valid index int the constellation vector, in other words
constellation(0)
would throw an error, because there is no "zeroth element". So, I presume this person adds the 1 to get valid indexing.
They could also have done
symbols = randi([1 4], 1, 256); % Note that I changed the random numbers generated
constellation = [1+1i, -1+1i, -1-1i, 1-1i];
signal = constellation(symbols); % Note that I took away the +1
I'm not sure why they did not code it this way, but maybe the zeros are need later.
1 CommentoMostra -1 commenti meno recentiNascondi -1 commenti meno recenti
charu shree il 5 Lug 2023
@the cyclist, Thanks a lot sir for such a wonderful response...

Accedi per commentare.

Più risposte (1)

Paul il 5 Lug 2023
Modificato: Paul il 5 Lug 2023
The elements in symbols range from 0 - 3, but Matlab uses 1-based indexing, i.e. the indices int0 constellation can only be 1-4.
1 CommentoMostra -1 commenti meno recentiNascondi -1 commenti meno recenti
charu shree il 5 Lug 2023
@Paul, Thank u so much sir for the reply...

Accedi per commentare.