A First Course in Scientific Computing
Rubin H. Landau · Princeton University Press eBooks · 2005
or formal concepts pervade mathematics and science because they make it easier to describe nature. For example, we often use the symbol v(t) to denote the velocity of an object as a function of time. Despite velocity being a familiar concept, it is actually abstract in the sense that we cannot see it. What we see is the position of the object as a function of time, and then we infer from that the velocity by determining how rapidly that position is changing. In computer science (CS), we create an abstract object by using a symbol to describe a collection of items. We have already seen that data, or variables in Java or Fortran may be integers, floating-point numbers, Booleans, or strings. These types of variables are built into the languages and therefore are called primitive data types. In addition, computer languages let the user define abstract data types of their own by combining primitive data types into more complicated structures called objects. These objects are abstract in the sense that they are named with a single symbol, yet they represent a number of parts.