# Calculates return value and standard error given a return period of interest

### Description

Calculates return value (also known as the return level) given a return period of interest, using model fit from `extRemes::fevd`

. Standard error is obtained via the delta method. The return value is the value for which the expected number of blocks until an event that exceeds that value is equal to the return period. For non-stationary models (those that include covariates for the location, scale, and/or shape parameters, return values and standard errors are returned for as many sets of covariates as provided.

### Usage

1 | ```
calc_returnValue_fevd(fit, returnPeriod, covariates = NULL)
``` |

### Arguments

`fit` |
fitted object from extRemes |

`returnPeriod` |
value for which return value is desired |

`covariates` |
matrix of covariate values, each row a set of covariates for which the return value is desired |