# 2-dimentional Radial Spline

### Description

2-dimentional radial spline generator used in `cpglmm`

### Usage

1 2 3 4 |

### Arguments

`x1` |
the first covariate in the coordinate |

`x2` |
the second covariate in the coordinate |

`k` |
number of knots |

`by` |
not used. This is just for compatibility with |

`allPen` |
not used. This is just for compatibility with |

`varying` |
not used. This is just for compatibility with |

`diag` |
not used. This is just for compatibility with |

`knots1` |
vector of knot locations for the first covariate in the coordinate |

`knots2` |
vector of knot locations for the second covariate in the coordinate |

### Author(s)

Fabian Scheipl fabian.scheipl@googlemail.com