**Block Category:** Matrix Operation

**Description:** The csd block (Cross Spectral Density)
takes two time-series buffers and performs FFT on both. Then it performs a
complex multiply of the first FFT by the complex conjugate of the second FFT.
The resulting magnitude and phase are put on the two block outputs.

The effect of multiplying by the complex conjugate is to give a 0-imaginary value when the two complex points are equivalent. This means that if both signals share a similarÂ frequency magnitude peak and are in phase, the resulting phase of the multiply is 0. If there is a phase difference, it is seen in the phase output.

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**Label:** Indicates a user-defined block label that appears when
**View > Block Labels** is activated.