Complex sentence: From this perspective the Dirac delta can usually be manipulated as though it were a function, and after its introduction the formal rules obeyed by the delta "function" were incorporated into the operational calculus, a standard tool kit of physics and engineering.
Split into simpler sentences: From this perspective the Dirac delta can usually be manipulated as though it were a function. The formal rules obeyed by the delta "function" are part of the operational calculus, a standard tool kit of physics and engineering.