matrix automation problem

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joey vergara
joey vergara on 2 May 2012
[c21 c11 c21 0 0 0 0 0 0 0; 0 c21 c11 c21 0 0 0 0 0 0; 0 0 c21 c11 c21 0 0 0 0 0; 0 0 0 c21 c11 c21 0 0 0 0; 0 0 0 0 c21 c11 c21 0 0 0; 0 0 0 0 0 c21 c11 c21 0 0; 0 0 0 0 0 0 c21 c11 c21 0; 0 0 0 0 0 0 0 c21 c11 c21] where the amount of rows/columns depends on a variable m and n respectively m=n-2
and n=10 in this case
how do i "automate" this??? TIA

Answers (1)

Richard Brown
Richard Brown on 2 May 2012
This is one annoying case where the sparse version spdiags can do more than the full one diag
n = 10;
m = n-2;
c11 = 1;
c21 = 2;
B = repmat([c21 c11 c21], m, 1);
A = spdiags(B, [0 1 2], m, n);
You might want to use
A = full(spdiags(B, [0 1 2], m, n));
if you don't want a sparse matrix.

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