The normal-speed calculation

For the local branch data reported in VIII-B, the calculation is

The arithmetic follows directly from (eq:normal-speed). The geometric construction establishing those branch data belongs to VIII-B CheungVIIIB; it is not reconstructed by the table.

In oblique cone coordinates, the gradient norm must be computed with the inverse physical Gram matrix, not with the Euclidean norm of the coordinate covector. Formula (eq:normal-speed) is coordinate independent.