How do I concatenate properly?

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

[Gonzalo]

The code in % is where I tried to concatenate but I keep getting the error "Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters."

[Torsten]

Concatenation would be

xx = [xx,xnew]

I don't know exactly what you try do do with the xx array.

[Cris LaPierre]

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]

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

Answer 1

[Cris LaPierre]

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