# Calculate the group 4 IHA parameters.

### Description

The group 4 IHA parameters measure the frequency and duration of high and low pulses.

### Usage

1 2 |

### Arguments

`thresholds` |
vector of length 2; the cut off for a low pulse and a high pulse, respectively |

`x` |
A zoo object containing the flow series |

`year` |
the type of year factor to be used, |

### Details

By default, the pulse thresholds are the 25th and 75th
percentiles of the distribution of flows. TNC's IHA
software uses the quantile as defined
http://www.roguewave.com/portals/0/products/imsl-numerical-libraries/c-library/docs/8.0/html/cstat/stat.htm
which corresponds to R's `type = 6`

option in
quantile. The default thresholds here are
calculated using R's default `type = 7`

option.

### Value

a matrix of group 3 parameters

### Author(s)

jason.e.law@gmail.com

### References

http://www.conservationgateway.org/Files/Pages/indicators-hydrologic-altaspx47.aspx

### Examples

1 2 |