Determines the terminal halflife of a sequence of corresponding times and values with optional minimum and maximum times to censor data.

## Usage

`calculate_halflife(times = NULL, values = NULL, tmin = NULL, tmax = NULL)`

## Arguments

- times
- sequence of times

- values
- corresponding sequence of values

- tmin
- minimum time to include (`NULL`

)

- tmax
- maximum time to include (`NULL`

)

## Value

List with the following names

thalf Halflife in units of times above

mod Result of lm used to fit the log transformed data

df Dataframe with the data and predicted values at the time within tmin and tmax

## Examples

```
x = c(0:100)
y = exp(-.1*x)
th = calculate_halflife(times=x, values=y)
#> Warning: essentially perfect fit: summary may be unreliable
#> Warning: essentially perfect fit: summary may be unreliable
thalf = th$thalf
```