This is a wrapper around `msm::MatrixExp()`

that computes the exponential
of multiple square matrices.

`expmat(x, t = 1, ...)`

- x
An array of matrices.

- t
An optional scaling factor for

`x`

.- ...
Arguments to pass to

`msm::MatrixExp()`

.

Returns an array of exponentiated matrices. If `length(t) > 1`

, then
`length(t)`

arrays are returned for each element in `x`

.

This function is most useful when exponentiating transition intensity
matrices to produce transition probability matrices. To create transition
probability matrices for discrete time state transition models with annual
cycles, set `t=1`

. An array of matrices is returned which can be used
to create the `value`

element of a `tparams_transprobs`

object. See
`qmatrix()`

for an example.