Function vector_wave_pullback 

pub fn vector_wave_pullback(
    family: Family,
    label: WaveLabel,
    args: [Complex; 6],
    helicity: bool,
    cotangent: [Complex; 3],
) -> Result<[Complex; 6]>

The gradients of all six complex arguments of vector_wave for a cotangent of the wave. A real physical input takes the real part of its gradient.