Row orthogonality relations for a character table (source code)

= Row orthogonality relations for a character table

For irreducible complex characters $\chi,\psi$ of a finite group,
$$
\sum_{g\in G}\chi(g)\overline{\psi(g)}
=|G|\delta_{\chi\psi}.
$$
Equivalently, summing over conjugacy classes $C$ with representatives $c$ gives
$$
\sum_C|C|\chi(c)\overline{\psi(c)}
=|G|\delta_{\chi\psi}.
$$