Cartesian second-rank tensor (source code)

= Cartesian second-rank tensor
{c}
{title2=$T\prime=RTR^T$}

= Cartesian rank-two tensor
{c}
{synonym}

A Cartesian second-rank tensor has component matrix $T$ in each <orthonormal basis>, with transformation $T\prime=RTR^T$ under an orthogonal component change $R$. Both indices transform; this is why assigning arbitrary matrices independently in different bases does not define a <tensor>. The <determinant>, <trace>, and <Frobenius inner product> with another such tensor are unchanged by these basis transformations.