Description Usage Arguments Value Author(s) References See Also Examples

This function estimates the parameters of the Kappa distribution given the L-moments of the data in an L-moment object such as that returned by `lmoms`

. The relations between distribution parameters and L-moments are seen under `lmomkap`

, but of relevance to this documentation, the upper bounds of L-kurtosis (*τ_4*) and a function of L-skew (*τ_3*) is given by

*τ_4 < \frac{5τ_3^2+1}{6}*

This bounds is equal to the Generalized Logistic distribution (`parglo`

) and failure occurs if this upper bounds is exceeded. However, the argument `snap.tau4`

, if set, will set *τ_4* equal to the upper bounds of *τ_4* of the distribution to the relation above. This value of *τ_4* should be close enough numerically The argument `nudge.tau4`

is provided to offset *τ_4* downward just a little. This keeps the relation operator as “*<*” in the bounds above to match Hosking's tradition as his sources declare “*≥*” as above the GLO. The nudge here hence is not zero, which is a little different compared to the conceptually similar snapping in `paraep4`

.

1 2 |

`lmom` |
An L-moment object created by |

`checklmom` |
Should the |

`snap.tau4` |
A logical to “snap” the |

`nudge.tau4` |
An offset to the snapping of |

`...` |
Other arguments to pass. |

An **R** `list`

is returned.

`type` |
The type of distribution: |

`para` |
The parameters of the distribution. |

`source` |
The source of the parameters: “parkap”. |

`support` |
The support (or range) of the fitted distribution. |

`ifail` |
A numeric failure code. |

`ifailtext` |
A text message for the failure code. |

W.H. Asquith

Hosking, J.R.M., 1994, The four-parameter kappa distribution: IBM Journal of Reserach and Development, v. 38, no. 3, pp. 251–258.

Hosking, J.R.M., and Wallis, J.R., 1997, Regional frequency analysis—An approach based on L-moments: Cambridge University Press.

`lmomkap`

,
`cdfkap`

, `pdfkap`

, `quakap`

1 2 3 4 5 6 |

```
$type
[1] "kap"
$para
xi alpha kappa h
-0.03276148 1.26628252 0.94534247 0.10277668
$source
[1] "parkap"
$support
lower upper
-10.202315 1.306735
$ifail
[1] 0
$ifailtext
[1] "Successful parameter estimation."
$type
[1] "kap"
$para
xi alpha kappa h
0 0 0 0
$source
[1] "parkap"
$support
[1] NA NA
$ifail
[1] 2
$ifailtext
[1] "TAU3 and TAU4 are above Generalized Logistic line."
```

Embedding an R snippet on your website

Add the following code to your website.

For more information on customizing the embed code, read Embedding Snippets.