Compared with their predecessors, modern computers are fast. Even wearable computing devices today boast processing power that only a few human generations ago would have placed them in the pantheon of the fastest computers on the planet. No amount of computational power, however, will do us any good if the program we write makes poor use of processor cycles and memory. Throughout the present work, we have focused on trying to “get the job done” and have written our programs with a focus on accomplishing the science or engineering task at hand rather than the speed at which the program accomplishes the task.

For evolution by natural selection to work, hereditary material must vary between individuals and such variation must cause individual differences in traits that are directly, or indirectly, involved with reproductive fitness. In other words, genetic differences between individuals are the raw material of evolution, but only if those differences produce differences in traits that are subject to natural selection. Theodosius Dobzhansky’s assertion that biology only makes sense in the context of evolution makes it clear that genetic variation is a cornerstone of the entire field of biology. It is certainly the basis of behavior genetics, where we strive to understand the role of genetic differences in producing individual differences in behavior.

In previous chapters, we have used looping and array syntax to analyze data in arrays of a number of dimensions. When we used looping constructs to examine the elements of arrays, we also found that branching statements like the if statement enable us to do different calculations depending upon whether certain conditions are true or not. Is it possible, however, to include branching logic into array syntax and avoid writing loops while still doing different calculations depending on whether certain conditions are true or not? In this chapter, we examine array functions and constructs that enable us to do exactly that.

Groundwater is of vital importance for agricultural irrigation. In almost all countries, a significant portion of irrigation water is derived from groundwater using wells. In developing countries where farm holdings are small, one well may suffice but a number of wells are used in large farms. This chapter discusses rudimentary aspects of groundwater and wells from the perspective of irrigation. Although the material covered in the chapter is based on gross simplifications, it has been found to be useful nonetheless for irrigation purposes.

Take a moment to think about cells. Which type of cell is your favorite? If you were to ask biologists, you would likely get a wide variety of responses. Some might have a soft spot in their hearts for red blood cells, or liver cells, or maybe even single-celled organisms like bacteria. However, if you were to ask psychologists which cells they prefer, you would likely learn that most of them favor neurons. Because it is with neural mechanisms that animals access, process, and act on information. Neural activity underlies all behavior, and therefore neurons occupy a privileged position in psychology.

Channels are a vital part of irrigation systems. They are the link between the source of water and the irrigation field. Channels used in irrigation systems can be either erodible or non-erodible, or earthen or lined. Flow in channels is governed by the principles of hydraulics. This chapter discusses rudimentary aspects of hydraulics and the design of open channels.

Pumps are an integral part of many agricultural irrigation systems. A pump is used to lift groundwater to the ground surface, raise water from a lower elevation to a higher elevation, transport water, overcome friction, or generate pressure for the operation of sprinkler and trickle irrigation systems. This chapter discusses rudimentary aspects of pumps and their operation and selection.

In Chapter 9, we were introduced to objects and object-oriented programming (OOP). In the objects we considered, however, the classes those objects were instances of were all written by others. We just made use of the templates or common patterns that describe the array, list, string, and other objects discussed in that chapter to make arrays, lists, strings, etc.