The GInorm function computes the norm of the Gaussian integer z.

A Gaussian integer z is a number of the form $z=a+\mathrm{I}b$ where a and  b are integers.

The norm of a Gaussian integer $z=a+\mathrm{I}b$ is defined as $\|\|z\|\|=\left(a+bI\right)\left(a-bI\right)=a^2+b^2$.

$\mathrm{with}\left(\mathrm{GaussInt}\right)\:$

$\mathrm{GInorm}\left(3+7\mathrm{I}\right)$

$58$