Computes a `n`

by `n`

matrix describing parasite dispersal from infecteds (columns)
to infectees (rows).
$$\mathcal{R} = b \beta \cdot {\cal V} \cdot \mbox{diag}\left(W \right) \cdot \beta^T \cdot \mbox{diag}\left(DH\right)$$

## Arguments

- b
transmission efficiency from mosquitoes to humans

- beta
the biting distribution matrix

- calV
parasite dispersal by mosquitoes matrix (see metric_calV)

- W
ambient human population at each patch

- D
human transmitting capacity

- H
human population size of each strata

## Value

a numeric matrix