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The normalization is such that 0 ≤ ''b<sup>2</sup>'' ≤ 1. | The normalization is such that 0 ≤ ''b<sup>2</sup>'' ≤ 1. | ||
The bicoherence is symmetric under the symmetries ''(ω<sub>1</sub>,ω<sub>2</sub>) | The bicoherence is symmetric under the symmetries ''(ω<sub>1</sub>,ω<sub>2</sub>) → (ω<sub>2</sub>,ω<sub>1</sub>)'' and | ||
''(ω<sub>1</sub>,ω<sub>2</sub>) | ''(ω<sub>1</sub>,ω<sub>2</sub>) → (-ω<sub>1</sub>,-ω<sub>2</sub>)'', so that only one quarter of the plane ''(ω<sub>1</sub>,ω<sub>2</sub>)'' contains independent information. | ||
Additionally, for discretely sampled data all frequencies must be less than the | Additionally, for discretely sampled data all frequencies must be less than the | ||
Nyquist frequency: ''ω<sub>1</sub>,ω<sub>2</sub>,ω ≤ ω<sub>Nyq</sub>''. These restrictions define a polygonal subspace of the plane, which is how the bicoherence is usually represented. | Nyquist frequency: ''ω<sub>1</sub>,ω<sub>2</sub>,ω ≤ ω<sub>Nyq</sub>''. These restrictions define a polygonal subspace of the plane, which is how the bicoherence is usually represented. |