The modulus of a complex number z, also called the complex norm, is denoted left bracketing bar z right bracketing bar and defined by left bracketing bar x + i y right bracketing bar congruent sqrt(x^2 + y^2). If z is expressed as a complex exponential (i.e., a phasor), then left bracketing bar r e^(i ϕ) right bracketing bar = left bracketing bar r right bracketing bar . The complex modulus is implemented in the Wolfram Language as Abs[z], or as Norm[z]. The square ( left bracketing bar z right bracketing bar )^2 of left bracketing bar z right bracketing bar is sometimes called the absolute square. Let c_1 congruent A e^(i ϕ_1) and c_2 congruent B e^(i ϕ_2) be two complex numbers.