The regulator of a number field is a positive number associated with . The regulator of an imaginary quadratic field is 1 and that of a real quadratic, imaginary cubic, or totally imaginary cubic field is the natural logarithm of the field's fundamental unit, i.e.,
There is also a more complicated definition for a general number field as the determinant of an matrix, where has real embeddings and imaginary embeddings and .
The regulator is implemented in the Wolfram Language for example as NumberFieldRegulator[Sqrt[d]].