What's the best way to create a vector with a repeating and diminutive sequence?

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Adam Quintero
Adam Quintero 2011-6-3
For a small example, how to create a version of this, with a longer seequence. These are integers of equal length apart:
v = 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 1 2 ....
and the starting sequence length will be scaled up into the 100s or 1000s.
Any thoughts?

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Matt Fig
Matt Fig 2011-6-3
N = 6;
A = cumsum(tril(ones(N,'single')));
A = A(A>0).';
If memory is a concern, this will conserve it:
L = (N^2+N)/2;
B = ones(1,L);
idx = (1:N).*((1:N)-1)/2;
Li = length(idx);
B(idx(2:Li)) = -(1:Li-1);
B = cumsum(B(L:-1:1));
  2 个评论
Adam Quintero
Adam Quintero 2011-6-3
I see where the initial sequence length is, and I am wondering how it would work if I wanted the sequence to decrease from the origin.
So:
v= [1 2 3 4 5 6 2 3 4 5 6 3 4 5 6 4 5 6 5 6 6]
I tried changing the sign of the 6 and the A>0 to A<0, and they didn't work. I think it shows here that I have a lot to learn. I appreciate the patience of anyone with feedback on this.
Thanx
Matt Fig
Matt Fig 2011-6-3
In that case, just reverse the order of two operations:
A = tril(cumsum(ones(N,'single')));

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