This function selects a bandwidth sigma
  for the kernel estimator of point process intensity
  computed by density.ppp.
The bandwidth \(\sigma\) is computed by the rule of thumb
  of Scott (1992, page 152). It is very fast to compute.
This rule is designed for density
  estimation, and typically produces a larger bandwidth
  than bw.diggle. It is useful for estimating
  gradual trend.