# elas

##### Calculate elasticity matrix

Calculate the elasticity matrix for a specified population matrix projection model using eigenvectors.

##### Usage

`elas(A, eval = "max")`

##### Arguments

- A
a square, non-negative numeric matrix of any dimension

- eval
the eigenvalue to evaluate. Default is

`eval="max"`

, which evaluates the dominant eigenvalue (the eigenvalue with largest REAL value: for imprimitive or reducible matrices this may not be the first eigenvalue). Otherwise, specifying e.g.`eval=2`

will evaluate elasticity of the eigenvalue with second-largest modulus.

##### Details

`elas`

uses the eigenvectors of `A`

to calculate the elasticity
matrix of the specified eigenvalue, see section 9.1 in Caswell (2001).
Same method as `elasticity`

in `popbio`

but can also evaluate
subdominant eigenvalues.

##### Value

A numeric (real or complex) matrix of equal dimension to `A`

.

##### References

Caswell (2001) Matrix Population Models 2nd ed. Sinauer.

##### See Also

Other PerturbationAnalyses: `sens`

,
`tfa_inertia`

, `tfa_lambda`

,
`tfam_inertia`

, `tfam_lambda`

,
`tfs_inertia`

, `tfs_lambda`

##### Examples

```
# NOT RUN {
# Create a 3x3 PPM
( A <- matrix(c(0,1,2,0.5,0.1,0,0,0.6,0.6), byrow=TRUE, ncol=3) )
# Calculate sensitivities of dominant eigenvalue
elas(A)
# Calculate sensitivities of first subdominant eigenvalue,
# only for observed transitions
elas(A, eval=2)
# }
```

*Documentation reproduced from package popdemo, version 1.3-0, License: GPL (>= 2)*