Let's say we have the complex vector $u=(1−i,2+3i)\in\mathbb C^2$.
How would I find the phase of $u$ ? I know that for a complex vector $z=(z_1,\ldots,z_n)$, its norm is defined by
$$||z||=\sqrt{\sum_{i=1}^nz_i\bar{z_i}}$$ But I don't know what is the phase of a complex vector, can anyone assist ? Thanks