Positive real axis

In mathematics, the set of positive real numbers, ${\displaystyle \mathbb {R} _{>0}=\left\{x\in \mathbb {R} \mid x>0\right\}}$, is the subset of those real numbers that are greater than zero.

In a complex plane, ${\displaystyle \mathbb {R} _{>0}}$ is identified with the positive real axis and is usually drawn as a horizontal ray. This ray is used as reference in the polar form of a complex number. The real positive axis corresponds to complex numbers ${\displaystyle z=|z|\mathrm {e} ^{\mathrm {i} \varphi }}$ with argument ${\displaystyle \varphi =0}$.

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