A Steady State is defined as a state for which a all time derivatives of the state variables $x_i$ are zero, i.e., \begin{equation} \frac{dx_i}{dt} = 0 \end{equation} Thus in the case that the variables $x_i$ are defined through a system of ordinary differential equations (ODEs) $dx_i/dt = f_i(t, x_1, ... x_l)$ the functions $f_i$ must all be zero in other words finding a Steady State is a root finding problem. The method used in COPASI to find a root is described in Steady State Calculation
To judge whether a found root is sufficiently close COPASI estimates the error using the following criterions:
