Built-In Mathcad Integrators

We will begin the learning of the integrators with the rkfixed function. It implements the fourth-order Runge-Kutta method (rk) with fixed step of integraticai (fixed). According to Mathcad syntax this function has five required arguments  

Creation of the array function f requires following a specific procedure. Usually this function is declared right before rkfixed using the following syntax  

The quantity of the array x elements as well as the quantity of the right-hand values is equal to the quantity of equations in the system. Let s clarify how rkfixed works by an example of a numerical solution of the direct problem for a three-step consecutive chemical reaction (Fig. 3.7). 

3 Numerical Solution of the Direct Problem in Chemical Kinetics 

Let s consider one of such problems. Certain microorganisms propagate in proportion to the colrniy size (with an aspect ratio k) but at the same time produce some excrement, which is a poison for them. 

---