A negative semidefinite matrix is a Hermitian matrix all of whose eigenvalues are nonpositive.
A matrix may be tested to determine if it is negative semidefinite in the Wolfram Language using NegativeSemidefiniteMatrixQ[m].
A negative semidefinite matrix is a Hermitian matrix all of whose eigenvalues are nonpositive.
A matrix may be tested to determine if it is negative semidefinite in the Wolfram Language using NegativeSemidefiniteMatrixQ[m].
Weisstein, Eric W. "Negative Semidefinite Matrix." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/NegativeSemidefiniteMatrix.html