## The possible numbers of zeros in an orthogonal matrix.(English)Zbl 0918.15007

It is shown that for $$n\geq 2$$ there is an $$n\times n$$ indecomposable orthogonal matrix with exactly $$k$$ entries equal to zero if and only if $$0\leq k\leq (n-2)^2$$.
Reviewer: G.Bonanno (Davis)

### MSC:

 15B57 Hermitian, skew-Hermitian, and related matrices 05C50 Graphs and linear algebra (matrices, eigenvalues, etc.)

### Keywords:

numbers of zeros; indecomposable matrix; orthogonal matrix
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