Introduction

Pad2ps series are tools to draw PAD figures of programs and algorithms.

PAD (Problem Analysis Diagram) is a diagram used to show the flow and the structure of a program. PAD is similar to the flowchart, which you are probably familiar with.

The flowchart is commonly known all over the world, and the reason behind this is probably because of its easiness to draw. The flowchart is very useful for thinking of a flow of a program, but it is not good at showing an algorithm, especially that of the structured programs. Here I show you some reasons. The first reason is that you need to read the flowchart from the top to the bottom, just along the flow, to understand the flowchart. This will be very obnoxious when trying to understand a program as a whole, especially when you are dealing with a huge program. The second reason is that because flowchart cannot show structures, flowcharts of identical algorithm, drawn by several people, will be very different, even if the algorithm consists of only one simple loop. Similarly, it may happen that there are two flowcharts look alike, but one is a branch and the other is a loop. These problems may be fatal when trying to show the algorithm.

PAD is a chart to show a flow and a structure of an algorithm. The main difference from flowchart is that PAD can clearly show the structure, such as the repetition and the conditional branching. To draw PAD you have to understand the algorithm fully, so it is a bit hard to draw PAD than drawing flowchart. But once you have finished drawing PAD, it should be fairly easy for other people to understand the processes and the structures of your algorithm.

Therefore, the flowchart is handy for diagraming programs written in BASIC-like languages, or languages with GOTO-like statement; as contrary, the PAD is good for expressing programs written in structured languages, such as C language. In any cases when you introduce algorithm in a book or in your report, or when you want to preserve the chart of your program for maintenance purpose, this PAD is most useful.

Pad2ps series are tools to draw PAD based on a text file without using any drawing tool. The source file's syntax, named PADEL (PAD Expression Language), is similar to that of C. You can also make them draw PAD figures directly from C, C++, Bourne shell, C shell, Java, and AWK program sources. The output styles can be selected from PostScript, LaTeX, and Encapsulated PostScript (EPS).

Many people had cooperated in making these pad2ps series. Mr. Satoshi Kuramochi has made the style file for LaTeXpad.sty and let me use it in pad2ps series. Besides he has helped me debugging and improving pad2tex from the beginning. Mr. Jun'ya Kato has cooperated fully in making the very first version of pad2ps series, to enable to handle Japanese, and so on. Mr. Makoto Iguchi has cooperated in making the English version of pad2ps and in translating the manuals in English. Mr. Takashi Osoegawa, Mr. Daisuke Fujii, and Mr. Koji Mikawa have gave me many and various profitable ideas and opinions. Some of them are not carried out yet, but they are to be done in the future. Besides I have received various bug information and improving ideas from many people. I really thank them again.

Nov. 2, 1996
Seiichi Yoshida

Go back to pad2ps - automatic PAD drawer.
Go back to Seiichi Yoshida's Home Page.
Sun Nov 10 01:36:04 JST 1996