Compute the derivatives for SIS compartmental model. Here, the model is computed in an equivalent form: $$ \begin{array}{rl} dH/dt = & B(t,H) + {\cal D} \cdot H \\ dI/dt = & h (H-I) - r I + {\cal D} \cdot I \end{array} $$ where \(S=H-I\) ; \(B(t, H)\) is the time-dependent birth rate; and the \(\cal D\) is the matrix describing demographic changes, including mortality, migration, and aging.
Usage
# S3 method for class 'SIS'
dXdt(t, y, pars, i)Value
a numeric vector