### Vector Cosine

For real vectors `x` and `y` having the same length,
we may compute the *vector cosine* by

cosxy = y' * x / ( norm(x) * norm(y) );For complex vectors, a good measure of orthogonality is the modulus of the vector cosine:

collinearity = abs(y' * x) / ( norm(x) * norm(y) );Thus, when

`collinearity`is near 0, the vectors

`x`and

`y`are substantially orthogonal. When

`collinearity`is close to 1, they are nearly collinear.

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