The absolute square of a complex number , also known as the squared norm, is defined as
(1)
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where denotes the complex conjugate of and is the complex modulus.
If the complex number is written , with and real, then the absolute square can be written
(2)
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If is a real number, then (1) simplifies to
(3)
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An absolute square can be computed in terms of and using the Wolfram Language command ComplexExpand[Abs[z]^2, TargetFunctions -> Conjugate].
An important identity involving the absolute square is given by
(4)
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(5)
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(6)
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If , then (6) becomes
(7)
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(8)
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If , and , then
(9)
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Finally,
(10)
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(11)
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(12)
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