A formula for the $g$-angle between two subspaces of a normed space

We develop the notion of $g$-angle between two subspaces of a normed space. In particular, we discuss the $g$-angle between a $1$-dimensional subspace and a $t$-dimensional subspace for $t\ge 1$ and the $g$-angle between a $2$-dimensional subspace and a $t$-dimensional subspace for $t\ge 2$. Moreover, we present an explicit formula for the $g$-angle between two subspaces of ${\mathrm{\ell }}^p$ spaces.