def unit_cell_to_lattice_array(cryst):
    """Return parallelpiped unit cell lattice matrix."""
    a_, b_, c_, alpha, beta, gamma = cryst
    # Convert angles from degrees to radians.
    r_alpha = np.deg2rad(alpha)
    r_beta = np.deg2rad(beta)
    r_gamma = np.deg2rad(gamma)
    # Calculate unit cell volume that is neccessary.
    volume = a_ * b_ * c_ * (
        1 - np.cos(r_alpha)**2 - np.cos(r_beta)**2 - np.cos(r_gamma)**2 + 2 *
        np.cos(r_alpha) * np.cos(r_beta) * np.cos(r_gamma))**0.5
    # Create the orthogonalisation Matrix (M^-1) - lattice matrix
    a_x = a_
    a_y = b_ * np.cos(r_gamma)
    a_z = c_ * np.cos(r_beta)
    b_x = 0
    b_y = b_ * np.sin(r_gamma)
    b_z = c_ * (
        np.cos(r_alpha) - np.cos(r_beta) * np.cos(r_gamma)) / np.sin(r_gamma)
    c_x = 0
    c_y = 0
    c_z = volume / (a_ * b_ * np.sin(r_gamma))
    lattice_array = np.array(
        [[a_x, a_y, a_z], [b_x, b_y, b_z], [c_x, c_y, c_z]])
    return lattice_array
Return parallelpiped unit cell lattice matrix.