Number Fields
《Number Fields》 · 第 123 页 · Chapter 6「The Distribution of Ideals in a Number Ring」，定义段
The quantity $\frac1n|\det(M)|$ is called the regulator of $R$ (or of $K$), written $\operatorname{reg}(R)$; equivalently it is the absolute value of the determinant formed from the log vectors of a fundamental system of units with the indicated final row.