# How do I concatenate properly?

3 vues (au cours des 30 derniers jours)
Gonzalo le 8 Sep 2022
Commenté : Torsten le 8 Sep 2022
for kk = 1:length(amps)
nStart = round(fs .* tStart(kk))+1; %-- add one to avoid zero index
xNew = shortSinus(amps(kk), freqs(kk), phases(kk), fs, durs(kk));
Lnew = length(xNew);
nStop = Lnew + nStart - 1; %======== Add code
xx(nStart:nStop) = xx(nStart:nStop) + xNew;
%xx(nStart + ((kk - 1)):...
% nStop + ((kk - 1))) ...
% = xx(nStart + ((kk - 1):...
% nStop + ((kk - 1)) + xNew;
end
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Cris LaPierre le 8 Sep 2022
This is not concatenation. This is indexing into and modifying an array. See Ch 5 of MATLAB Onramp for more on how to do this.
Torsten le 8 Sep 2022
This is horizontal concatenation of xx with xnew.
a = [1 2 3];
b = [4 5 6];
c1 = [a,b]
c1 = 1×6
1 2 3 4 5 6
c2 = horzcat(a,b)
c2 = 1×6
1 2 3 4 5 6

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### Réponses (1)

Cris LaPierre le 8 Sep 2022
Modifié(e) : Cris LaPierre le 8 Sep 2022
You need to put parentheses around your values to the left and right of the colon operators to force the order of operations to calculate a single value on each side.
xx(nStart + ((kk - 1)):nStop + ((kk - 1)))
should be
xx((nStart + kk - 1):(nStop + kk - 1))
Simplifying your example
xx=1:10
xx = 1×10
1 2 3 4 5 6 7 8 9 10
nStart = 2;
nStop = 5;
kk = 1;
xNew = 100;
xx((nStart + kk - 1):(nStop + kk - 1)) = xx((nStart + kk - 1):(nStop + kk - 1)) + xNew
xx = 1×10
1 102 103 104 105 6 7 8 9 10
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