tanerFC {astrochron} | R Documentation |

## Apply Taner bandpass or lowpass filter to Fourier coefficients

### Description

Apply Taner bandpass or lowpass filter to Fourier coefficients.

### Usage

```
tanerFC(fc,npts,flow=NULL,fhigh=NULL,roll=10^3,output=1,genplot=T,verbose=T)
```

### Arguments

`fc` |
Fourier coefficients, as output by the function 'periodogram'. The first column is frequency, the second column contains the real coefficients, and the third column contains the imaginary coefficients. |

`npts` |
The number of points in the stratigraphic series used to estimate the Fourier coefficients. |

`flow` |
Low frequency cut-off for Taner filter (half power point). If this value is not set (NULL), it will default to -1*fhigh, which will create a lowpass filter. |

`fhigh` |
High frequency cut-off for Taner filter (half power point). |

`roll` |
Roll-off rate, in dB/octave. Typical values are 10^3 to 10^12, but can be larger. |

`output` |
Output: (1) filtered series, (2) bandpass filter window. |

`genplot` |
Generate summary plots? (T or F) |

`verbose` |
Verbose output? (T or F) |

### Details

This function is designed for cases when one needs to efficiently apply a range of filter parameters to a stratigraphic series. It is used within function 'timeOpt' to speed up processing. For more general use, function 'taner' is preferred, which also provides a range of plots for evaluating the filtering.

Fourier coefficients for 'tanerFC' can be determined with the function 'periodogram', using options 'output=2' and 'nrm=0'.

### Value

bandpassed stratigraphic series.

### References

http://www.rocksolidimages.com/pdf/attrib_revisited.htm#_Toc328470897

### See Also

`bandpass`

, `lowpass`

, `noKernel`

, `noLow`

, `prewhiteAR`

, and `prewhiteAR1`

### Examples

```
# generate example series with periods of 405 ka, 100 ka, 40ka, and 20 ka, plus noise
ex=cycles(freqs=c(1/405,1/100,1/40,1/20),end=1000,dt=5,noisevar=.1)
# calculate the Fourier coefficients using periodogram function. this must be done with
# no normalization (nrm=0)
fc_ex <- periodogram(ex,demean=TRUE,output=2,nrm=0)
# bandpass precession term using Taner window
bandpass_ex <- tanerFC(fc=fc_ex,npts=201,flow=0.045,fhigh=0.055,roll=10^10)
# lowpass filter eccentricity terms using Taner window
lowpass_ex <- tanerFC(fc=fc_ex,npts=201,fhigh=.02,roll=10^10)
```

*astrochron*version 1.3 Index]