Free-PLOT Graphics Software System

Based on PGPLOT Graphics Subroutine Library by T. J. Pearson, a new graphics software system named Free-PLOT is developed on VAX 8350 in Yunnan Observatory. It in eludes nearly all advantages of PGPLOT in driving a lot of graphical equipments, to draw a polyline (curve defined by line-segments), to plot a histogram, to draw a contour map or a gray-scale map of an. array or an image. In addition, since it has some special graphical symbols (like triode, transformer's coil, mechanical gear), some basic geometric curves and powerful analytic geometric calculation functions, it could be as a preliminary tools of CAD to make circuit diagrams, mechanics diagrams, optics diagrams, etc. All of operation only uses 128 commands. So that it is very easy to be mastered, even for a person who has never leared any computer language. This paper mainly introduced the character, function and simple instruction of Frce-PLOT system.