Definition:Complex Modulus

Definition
Let $z = a + i b$ be a complex number, where $a, b \in \R$.

Then the (complex) modulus of $z$ is written $\cmod z$ and is defined as the square root of the sum of the squares of the real and imaginary parts:


 * $\cmod z := \sqrt {a^2 + b^2}$

The complex modulus is a real-valued function, and as when appropriate is referred to as the complex modulus function.

Also known as
The complex modulus is also known as the complex absolute value. Others use that term only for the absolute value of a real number.

The notation $\bmod z$ is sometimes seen for $\cmod z$, but on it is not recommended.

Also see

 * Modulus is Norm, showing that the modulus defines a norm on the field of complex numbers.
 * Modulus in Terms of Conjugate

Special cases

 * Definition:Absolute Value of Real Number, as shown at Complex Modulus of Real Number equals Absolute Value