Notation

Symbol	Definition
${\mathcal {H}}\,\!$			Hilbert Space
${\mathbb {C} }\,\!$			The set of complex numbers
Failed to parse (MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle {\mathbb{R}}\,\!}			The set of real numbers