Christoffel symbols

The Christoffel symbols are related to the metric tensor by

$\Gamma _{\mu \nu }^{\lambda }={\frac {1}{2}}g^{\lambda \rho }\left(g_{\mu \rho },_{\nu }+g_{\rho \nu },_{\mu }-g_{\mu \nu },_{\rho }\right)$

where the comma is a partial derivative. For example

$g_{\mu \nu },_{\rho }={\frac {\partial g_{\mu \nu }}{\partial x^{\rho }}}$

The Christoffel symbols are part of a covariant derivative opperation, represented by a semicolin or capitalized D ,mapping tensor elements to tensor elements. For example

$T^{\lambda };_{\rho }={\frac {DT^{\lambda }}{\partial x^{\rho }}}={\frac {\partial T^{\lambda }}{\partial x^{\rho }}}+\Gamma _{\mu \rho }^{\lambda }T^{\mu }$

Also for example

$T_{\lambda };_{\rho }={\frac {DT_{\lambda }}{\partial x^{\rho }}}={\frac {\partial T_{\lambda }}{\partial x^{\rho }}}-\Gamma _{\lambda \rho }^{\mu }T_{\mu }$