Let $A \in \mathbb{C}^{N \times N}$ be a D6159: Complex square matrix.
A D6159: Complex square matrix $B \in \mathbb{C}^{N \times N}$ is a square root for $A$ if and only if \begin{equation} A = B^2 \end{equation}

Let $A \in \mathbb{C}^{N \times N}$ be a D6159: Complex square matrix.
A D6159: Complex square matrix $B \in \mathbb{C}^{N \times N}$ is a square root for $A$ if and only if \begin{equation} A = B B \end{equation}