Package: fNonlinear
Check: R code for possible problems
New result: NOTE
  .lyapunovFit: no visible global function definition for ‘frequency’
  lyapunovPlot: no visible global function definition for ‘frequency’
  separationPlot: no visible global function definition for ‘frequency’
  Undefined global functions or variables:
    frequency
  Consider adding
    importFrom("stats", "frequency")
  to your NAMESPACE file.