## $$\pm$$ sign pattern matrices that allow orthogonality.(English)Zbl 1164.15327

Summary: A sign pattern $$A$$ is a $$\pm$$  sign pattern if $$A$$  has no zero entries. $$A$$  allows orthogonality if there exists a real orthogonal matrix  $$B$$ whose sign pattern equals  $$A$$. Some sufficient conditions are given for a sign pattern matrix to allow orthogonality, and a complete characterization is given for $$\pm$$ sign patterns with $$n-1 \leq N_-(A) \leq n+1$$ to allow orthogonality.

### MSC:

 15B36 Matrices of integers

### Keywords:

sign pattern; orthogonality; orthogonal matrix
Full Text:

### References:

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