makeNoise {astrochron} | R Documentation |

## Generate noise surrogates from a theoretical power spectrum

### Description

Generate noise surrogates from a theoretical power spectrum.

### Usage

```
makeNoise(S,dt=1,mean=0,sdev=1,addPt=F,nsim=1,genplot=T,verbose=T)
```

### Arguments

`S` |
Vector or 1-D data frame containing the theoretical power, from f(0) to the Nyquist frequency. |

`dt` |
Sampling interval for surrogate series |

`mean` |
Mean value for surrogate series |

`sdev` |
Standard deviation for surrogate series |

`addPt` |
Did you add a Nyquist frequency? (T or F) |

`nsim` |
Number of surrogate series to generate |

`genplot` |
generate summary plots (T or F) |

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

### Details

These simulations use the random number generator of Matsumoto and Nishimura [1998]. The algorithm of Timmer and Konig (1995) is employed to generate surrogates from any arbitrary theoretical power spectrum. See examples section below.

### References

M. Matsumoto, and T. Nishimura, (1998),
*Mersenne Twister: A 623-dimensionally equidistributed uniform pseudo-random number generator*, ACM Transactions on Modeling and Computer Simulation, 8, 3-30.

J. Timmer and K. Konig (1995),
*On Generating Power Law Noise*, Astronomy and Astrophysics: v. 300, p. 707-710.

### Examples

```
# create theoretical AR1 spectrum, using rho of 0.8
rho=0.8
freq=seq(0,.5,by=0.005)
Nyq=max(freq)
AR1 = (1-(0.8^2)) / ( 1 - (2*0.8*cos(pi*freq/Nyq)) + (0.8^2) )
plot(freq,AR1,type="l")
# make noise surrogates from the theoretical AR1 spectrum
makeNoise(AR1)
```

*astrochron*version 1.3 Index]