# Add the Hermetian conjugate to make Lagrangian real

1. Aug 16, 2015

### Lapidus

How does adding a h.c. term make a Lagrangian real? Like here on page 99 (11.51)?

thanks in advance

2. Aug 16, 2015

### Staff: Mentor

You add something with the same real part but with the negative imaginary part. The sum has an imaginary component of zero.

$z + \bar z$ is always real (even if you replace z by more complex structures).

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