hello everyone ,

i have just recently got an investigation in which i have to model sine functions of sunrise, sunset and daylight for two different cities in two different continents. i Have chosen to do Quito in Ecuador and Lisbon in Portugal. i have successfully modelled functions for calculating the sunset, sunrise and daylight time disregarding the day light saving time. but now, i am stuck on question 8. this is the question-

8. Improve your functions in 6 taking summer saving time into consideration

how will i come up with a function fot his??

this follwoing link shows the graph with daylight saving which i have to make-

Lisbon, Portugal - Sunrise, sunset, dawn and dusk times for the whole year - Gaisma

any help will be appreciated thanks