factor by which to scale the arrows when visualising a spatially-varying kernel
Details
The function show_kernel adapts its behaviour to the type of kernel. If the kernel is spatially-invariant, then the kernel with \(s\) evaluated at the origin is plotted. If spatially-variant, then arrows on a regular grid over the domain are plotted. The direction of the arrow is indicative of the transport direction at a specific location, while the length of the arrow is indicative of the transport intensity.