Method for calculating mean lifespan, given the natural mortality

Description

For an FLBiol object with the natural mortality-at-age present in the object.

Usage

mean.lifespan(x, ...)

Arguments

Details

Using actuarial definitions for the expected life-span of a given species, for a given survival rate-at-age (natural mortality), we can compute the expected life-span, $ell_x$, of a species, from a given reference age $x$, using the following equation:

ell_x = sumlimits_{t=1}^{infty} exp(-sumlimits_{i=x}^{x+t}M_i)

.

The method accepts objects of class FLbiol of any particular dimension. If the object has a seasonal structure to the population dynamics, then we sum over all seasons to get the yearly survival rate.

Value

An object of class FLQuant-class whose first and second dimension is of length one.

Author(s)

FLR Team

See Also

FLBiol-class

Examples

## Not run: 
data(ple4biol)
lfs.ple4 <- mean.lifespan(ple4,ref.age=1)
## End(Not run)