When an algorithm says Summation this, and Integral that, what does it mean in coding terms?
You are probably looking at a rather mathematical sketch of an algorithm. There are two general roads to implement non-trivial mathematical expressions such as series, integrals, and differential equations.


If you want exact, potentially symbolic results you have to simplify "complex" expressions into closed forms on paper, and/or employ computer algebra.
If you are satisfied with numerical, potentially approximate solutions, you want to employ numerical algorithms, including error estimations.