Repetitive sequence with calculations

Hello all,

I am trying to create the following sequence of numbers:

5 6 7 5 6 7 5 6 7 8 9 10 8 9 10 8 9 10 11 12 13 ...

To be more specific, 5 6 7 will be repeated three times and then +1 to each element and repeat another three times. The amount of iterations would be pre-defined f.e. n times.

This is what I tried but it didn't work:

a=[5 6 7]

x = []

n=9

for i=1:n

s=3+a

for j=1:3

m(i,j)=s(i)

end

b=s+3

x = [x,b];

end

Huge thanks in advance!

Answer 1

[David Hill]

a=[5 6 7];
x=zeros(1,9*n);
for j=1:n
    x(9*(j-1)+1:9*j)=repmat(a,1,3);
    a=a+3;
end

[Kyrylo Melnyk]

David,

Thanks a lot!

Sorry to bother you but I have another question. If I want to increase the amount of numbers to [5 6 7 8] and then +1 to each element, repeat them 4 times (repeat those steps N times). Basically, what I am trying to say is that I want to change the width (f.e. variable M) of that repetitive component but it doesn't work if I just change '3' to '4'. This is what I tried to do:

n=9;

x=[]

a=[5 6 7 8];

x=zeros(1,9*n);

for j=1:n

x(9*(j-1)+1:9*j)=repmat(a,1,4);

a=a+4;

end

In another words what I really want:

1. repeat M components for M-times ( 1 2 1 2 next sequence is 3 4 3 4 ..)
2. add +M to each element after the first step
3. Repeat this whole process for N times ( f.e. I want to repeat steps 1 and 2 for 15 times)

[David Hill]

N=15;
M=[5 6 7 8];
x=zeros(1,length(M)^2*N);
for j=1:N
    x(length(M)^2*(j-1)+1:length(M)^2*j)=repmat(M,1,length(M));
    M=M+length(M);
end

[Kyrylo Melnyk]

Thank you so much!

[Stephen23]

Simpler without a loop, here using repelem:

>> L = numel(M);
>> x = repmat(M,1,L*N) + repelem(L*(0:N-1),L*L)

or using kron:

>> x = repmat(M,1,L*N) + kron(0:N-1,L*ones(1,L*L))