The BogackiâÂÂShampine method is a method for the numerical solution of ordinary differential equations, that was proposed by Przemysà Âaw Bogacki and Lawrence F. Shampine in 1989 . The BogackiâÂÂShampine method is a RungeâÂÂKutta method of order three with four stages with the First Same As Last (FSAL) property, so that it uses approximately three function evaluations per step. It has an embedded second-order method which can be used to implement adaptive step size. The BogackiâÂÂShampine method is implemented in the <code>ode3</code> for fixed step solver and <code>ode23</code> for a variable step solver function in MATLAB .
Low-order methods are more suitable than higher-order methods like the DormandâÂÂPrince method of order five, if only a crude approximation to the solution is required. Bogacki and Shampine argue that their method outperforms other third-order methods with an embedded method of order two.
The Butcher tableau for the BogackiâÂÂShampine method is:
Following the standard notation, the differential equation to be solved is . Furthermore, denotes the numerical solution at time and is the step size, defined by . Then, one step of the BogackiâÂÂShampine method is given by:
Here, is a second-order approximation to the exact solution. The method for calculating is due to . On the other hand, is a third-order approximation, so the difference between and can be used to adapt the step size. The FSALâÂÂfirst same as lastâÂÂproperty is that the stage value in one step equals in the next step; thus, only three function evaluations are needed per step.