discontinuous coefficientsa vaccination campaign what about modeling vaccination campaignimagine that six days after the outbreak of the diseasethe local health station launches vaccination campaign they reach out to many peoplesay times as efficiently as in the previous (constant vaccinationcase if the campaign lasts for days we can write td : otherwise note that we must multiply the value by because is measured in hoursnot days in the differential equation systemps tmust be replaced by / /and in this case we get differential equation system with term that is discontinuous this is usually quite challenge in mathematicsbut as long as we solve the equations numerically in programa discontinuous coefficient is easy to treat there are two ways to implement the discontinuous coefficient /through function and through an array the function approach is perhaps the easiestdef ( )return if ( * < < * else in the code for updating the arrays and we get term ( [ ])* [nwe can also let tbe an array filled with correct values prior to the simulation then we need to allocate an array of length n_t+ and find the indices corresponding to the time period between and days these indices are found from the time point divided by that isp zeros(n_t+ start_index * /dt stop_index * /dt [start_index:stop_index the / tterm in the updating formulas for and simply becomes [ ]* [nthe file sirv py contains program based on filling an array the effect of vaccination campaign is illustrated in fig all the data are as in fig (left)except that is ten times stronger for period of days and elsewhere