There are many students and professionals in science and engineering, other than those specifically interested in fields such as computer science or computer engineering, who need to know how to solve computational problems on computers. There are basically two approaches to meeting the needs of such people. One is to rely on software applications such as spreadsheets, using built-in functions and perhaps user-defined macros, without requiring any explicit understanding of the principles on which programming languages are based.

A second approach is to learn a programming language, previously Fortran or Pascal, and more recently C, C++, or Java. These languages are important for certain kinds of work, such as computer science or scientific computing, but they may be viewed, possibly with good reason, as irrelevant by many students and professionals.

From a student’s point of view, there is no painless solution to this dilemma, but in this book I assume that learning to solve computational problems in an online environment using HTML,1 JavaScript, and PHP will at least appear to be a more relevant approach. HTML and JavaScript are universally used for developing self-contained online applications. The use of PHP for accessing externally stored data files, a capability that is not available directly through JavaScript, greatly extends the range of science and engineering problems that can be addressed. A working knowledge of these programming languages is a valuable skill for any scientist or engineer. The fact that these are Web-based languages may make such skills more immediately marketable than comparable skills developed with older text-based languages.