Subroutines Help Software Programmers Avoid Having To 'Reinvent The Wheel'

When writing computer programs in any language, scientists must solve problems that probably have been faced already by many other programmers. It is silly to "reinvent the wheel," as the saying goes, when a variety of routines (subprograms that scientists can plug into programs they're writing) are already available for the most popular computer languages. I spend most of my time programming in Turbo Pascal 4.0 (produced by Borland International), so I am most familiar with the three classes of routines specific to this high-level programming language. The three classes are: general collections, which simplify the process of designing screens that will appear in a program; graphics-focused collections, for quickly and easily drawing geometric shapes; and sets of scientific routines, which make it easier for scientists to add geometric and mathematical formulas to scientific programs. General Routines General screen routines are subprograms that can be put into a program to manipulate the basic elements that will appear on the screen. I reviewed three packages of general purpose routines: Nostradamus' Turbo Plus, Blaise's Turbo Power Tools Plus, and Turbo Power's Turbo Professional. The similarity of names is confusing, so I'll refer to them as Nostradamus, Blaise, and TProf. All of these packages offer better control of the screen and keyboard than Turbo Pascal provides and also offer string-handling functions, which manipulate sets of characters on the screen. TProf is the only one that will do simple sorting, and Nostradamus has mouse support and routines that allow sounds—beeps, buzzes, and so on—to be included in a program. TProf has almost 400 functions, which are program commands each invoked by a different keystroke. While Blaise has only about 200 functions, many of them can be invoked by an additional parameter, or combination of program commands, which effectively gives Blaise as many functions as TProf. For example, TProf has two separate functions for writing on the screen each one writes in a different color. Blaise, on the other hand, has only one function for writing on the screen, but an additional parameter is available that can switch colors with one extra keystroke. Nostradamus has only about 150 functions but includes a screen editor, which allows the programmer to write and edit the program that determines the text that will appear on a screen and where it will be placed (The Scientist, September 5, page 22). Basically, the number of things a programmer can do with TProf and Blaise is about the same, and about twice as much as is possible with Nostradamus. The Nostradamus product is quite different from TProf and Blaise in other respects as well. The package has two serious flaws: It provides no source code (the text life that the programmer creates and which is later compiled into code the machine understands) for the routines; and its documentation is poor—the manual has no index and the programmer will only be able to decipher the purpose of some functions by carefully studying the sample programs. Source code for each routine, which is included with TProf and Blaise, is an invaluable learning device—it can be used as a tool for understanding what the functions are doing and for modifying the packages' programs. TProf has two features of special interest to scientists: support for large arrays (storage areas in memory) and a sort routine for grouping items in a particular order. With Turbo Pascal, any array is limited to 64K bytes of storage, which is the equivalent of about a 100 X 100 matrix of real numbers. For scientific programs, where real numbers take up lots of storage space (real numbers require six bytes while integers, for example, only require two), 64K is just not enough. TProf will take advantage of any hardware memory add-ons, such as extended or expanded memory, or it will even work with virtual memory, which stores information temporarily on disk, to handle huge data structures. In addition, TProf comes with a disk of additional routines including a public domain mouse unit and a routine that makes a scrolling list of files pop up on the screen. Blaise is a well-done set of routines, but given TProf's excellent array support, TProf is clearly the best choice for scientists. Nostradamus should be considered primarily a screen/input generator with extra routines, so it might make sense to use it in conjunction with TProf, but not as a substitute. Graphics Collections The general routines described above can only handle text functions. But while Turbo Pascal has an impressive set of graphics routines built-in (including multiple fonts and support for many graphics monitors), scientists who do a lot of graphics programming should consider one of two sets of graphics toolkits: Metagraphics' TurboWindow Pascal and Borland's own Graphix Toolbox. TWindow has several advantages it supports more monitor types than Graphix Toolbox, it can be upgraded to versions that support additional languages and higher-resolution monitors, and it has excellent mouse support in graphics mode. While I didn't do formal tests, it also seems faster at displaying graphics. However, the Borland toolbox includes many more geometric shapes, so the choice isn't entirely clear-cut. I think most scientists would be happier with TWindow, but for someone who needs the extra geometric objects that Graphix Toolbox provides, Borland's package is the best choice. Scientific Routines Four collections of routines involving numerical or geometrical analysis are available for use in scientific programs. These packages offer routines that can multiply matrices, find the zeros of a polynomial, or determine the volume of a pyramid from its coordinates. Turbo Geometry Library is a collection of over 200 procedures covering a wide range of simple geometric formulas from the vertices of a regular inscribed polygon inside a circle, to the intersection of planes and areas of various objects. No conic sections are available, but the program includes spine and bezier curve fitting. All of these are fairly simple graphics functions, and they are not optimized for speed, but it is useful to have them all one place. Borland's Numerical Methods Toolbox, Precision Plus Software's MathPak 87, and Quinn-Curtis' Science and Engineering Tools are comparable collections of numerical routines, and the Quinn-Curtis package also includes graphics routines. The numerical routines feature polynomial solving, curve fitting, numerical integration and differentiation, fast Fourier transforms, and matrix functions like eigenvalues. I regard the Quinn-Curtis package as unacceptable—not only does it fail to use a numeric coprocessor or any assembly language routines, but the package includes fatal Pascal language errors involving how functions are passed to its units and the proper location of pointers. I recommend MathPak 87 for anyone programming with a numeric coprocessor, because it has more powerful routines and is mainly coded in assembly language, which is efficient and fast. Barzy Simon is IBM Professor of Mathematics and Theoretical Physics at Caltech.

Subroutines Help Software Programmers Avoid Having To 'Reinvent The Wheel'

General Routines

Interested in reading more?

Become a Member of