# Estimate temporal coefficients of selection assuming no fluctuating selection

### Description

`nfs`

is a function which estimates the temporal covariance matrix
and the temporal mean alpha coefficients (i.e. directional
selection) under the assumption of no fluctuating selection.

### Usage

1 | ```
nfs(At, at, npar, nyear)
``` |

### Arguments

`At` |
a list containing the named yearly variance-covariance matrices. Sorted by year. |

`at` |
a list containing the named yearly vectors of the estimated selection coefficients. Sorted by year. |

`npar` |
the number of parameters in the model for the estimates selection coefficients. |

`nyear` |
the number of years with estimates of selection. |

### Details

`nfs`

is used internally in `lmf`

when estimating temporal mean
coefficients of selection under the assumption of no fluctuating selection, but
given the right data can be executed as a standalone. The input to the
arguments At and at are estimated within `lmf`

by correctly combining
estimates of coefficients and variance-covariance within each age class and year
to a estimate for each year.

Engen et al. 2012 describe the method in details.

### Value

`nfs`

returns a list containing the following components:

`Anf` |
the estimated temporal covariance matrix under the assumption of no flucutating selection. |

`anf` |
the estimated temporal mean selection coefficients under the assumption of no fluctuating selection. |

### Author(s)

Thomas Kvalnes

### References

Engen, S., Saether, B.-E., Kvalnes, T. and Jensen, H. 2012. Estimating fluctuating selection in age-structured populations. Journal of Evolutionary Biology, 25, 1487-1499.

### See Also

`lmf`

, `fs`

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 | ```
#Data set from Engen et al. 2012
data(sparrowdata)
#Fit model
lmf.1 <- lmf(formula = cbind(recruits, survival) ~ weight + tars,
age = age, year = year, data = sparrowdata)
#Extract At and at
At <- lmf.1$At
at <- lmf.1$at
#Estimate temporal selection coefficients under the assumption of no
#fluctuating selection
noflusel <- nfs(At = At, at = at, npar = 3, nyear = 7)
#View output
str(noflusel)
noflusel
``` |