gam.reparam {mgcv} | R Documentation |

## Finding stable orthogonal re-parameterization of the square root penalty.

### Description

INTERNAL function for finding an orthogonal re-parameterization which avoids "dominant machine zero leakage" between components of the square root penalty.

### Usage

```
gam.reparam(rS, lsp, deriv)
```

### Arguments

`rS` |
list of the square root penalties: last entry is root of
fixed penalty, if |

`lsp` |
vector of log smoothing parameters. |

`deriv` |
if |

### Value

A list containing

`S`

: the total penalty matrix similarity transformed for stability.`rS`

: the component square roots, transformed in the same way.`Qs`

: the orthogonal transformation matrix`S = t(Qs)%*%S0%*%Qs`

, where`S0`

is the untransformed total penalty implied by`sp`

and`rS`

on input.`det`

: log|S|.`det1`

: dlog|S|/dlog(sp) if`deriv >0`

.`det2`

: hessian of log|S| wrt log(sp) if`deriv>1`

.

### Author(s)

Simon N. Wood <simon.wood@r-project.org>.

*mgcv*version 1.9-1 Index]