We study ranks of the $r\textrm{ th}$ Hadamard powers of doubly nonnegative matrices and show that the matrix $A^{ \circ r}$ is positive definite for every $n\times n$ doubly nonnegative matrix $A$ and for every $r>n-2$ if and only if no column of $A$ is a scalar multiple of any other column of $A.$ A particular emphasis is given to the study of rank, positivity and monotonicity of Hadamard powers of rank two, positive semidefinite matrices that have all entries positive.

Categories: math.CA math.RA

Hadamard powers of rank two, doubly nonnegative matrices