Follow conversation on m_spectrum_ph3.py

          ```python
    def conj_prod(x, y, key):
        prod = x * y.conj() 
        return prod.real if key.startswith("P") else prod.imag

    keys = ["P11", "P22", "P33", "Q12", "Q13", "Q23", "P13", "P12", "P23"]
    index_pairs = [
        (0, 0),
        (1, 1),
        (2, 2),
        (0, 1),
        (0, 2),
        (1, 2),
        (0, 2),
        (0, 1),
        (1, 2),
    ]

    mom = {
        key: conj_prod(X[i, 1:], X[j, 1:], key)
        for key, (i, j) in zip(keys, index_pairs)
    }

_Originally posted by @cpaniaguam in https://github.com/brown-ccv/icesat2waves/pull/131#discussion_r1517936436_

brown-ccv / icesat2waves

Follow conversation on m_spectrum_ph3.py #193