For each \((\omega, ho)\), deduce that the matrix-valued function

\[
M_{v}\left(\left\|x-x^{\prime}ight\|ight)\left(\cos \left(\omega^{\prime}\left(x-x^{\prime}ight)ight) I_{3}-\sin \left(\omega^{\prime}\left(x-x^{\prime}ight)ight) \chi(ho)ight)
\]

is the covariance function for a stationary Gaussian process \(Z: \mathbb{R}^{3} ightarrow \mathbb{R}^{3}\).