Qeybta hoos ku qoran ka dibna ka jawaab su'aasha ka dib luqadda la mid ah sida marinka: Qeybta: The calculus of kala duwanaanshaha waxaa ka walaacsan ugu badnaan ama ugu yar (si wadajir ah loo yaqaan xagjirka ah) ee functionals. functional A maps hawlaha si scalars, sidaa functionals ayaa lagu tilmaamay sida "hawlaha hawlaha". Functionals leeyihiin xagjirka ah ee la xiriirta xubno ka y of meel functional la siiyo qeexay domain a la siiyo. functional A J [ y ] ayaa sheegay in ay leeyihiin extremum at function f haddii ΔJ = J [ y ] − J [ f ] ayaa calaamad isku mid ah oo dhan y ee xaafadda yar ee si macquul ah function ee f. F waxaa loo yaqaan functional xagjirka ah ama xagjirka ah. J [ f ] waxaa loo yaqaan ugu badnaan maxaliga ah haddii ΔJ ≤ 0 ee xaafadda yar ee si macquul ah ee f, iyo ugu badnaan maxaliga ah haddii ΔJ ≥ 0.
xad dhaaf