C-number
- For the use of C-numbers for the classification of Corydoras species see Corydoras.
The term C-number is an old nomenclature used by Dirac to distinguish between real or complex numbers (c-numbers or classical numbers) and operators (q-numbers or quantum numbers) in quantum mechanics.
Although c-numbers are commuting, in physics the term anti-commuting c-number is used to refer to a type of anti-commuting numbers that are mathematically described by Grassmann numbers.