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DCL:GRPH2:U[XYZ]PACK: Cartesian Coordinate Axis Routines

3.1 Summary

The UXPACK/UYPACK/UZPACK are subroutine packages for plotting the coordinate axes in a Cartesian coordinate system. Therefore, they can only be used for normalization transformations with transformation function numbers ITR=1-4 (in a Cartesian coordinate system). The program is not certified to operate properly when other transformation function numbers are specified.

The packages for coordinate axes such as  ULPACK (Chapter 4),  UCPACK (Chapter 5), and USPACK (Chapter 7) are designed based on this package.

The functions of theUXPACK/UYPACK/UZPACK packages are as follows.

UXPACK	: Plots the x axis
UYPACK	: Plots the Y axis
UZPACK	: Handles internal variables and performs initialization

The UXPACK and UYPACK consist of subroutine groups on 3 levels.

1.

Basic Routines: Subroutines that performs the basic drawing operations. The user is not required to know them. 

2.

Lower Level Applications: A group of subroutines that are written using the basic routines, and which perform the actual drawing . (Will be abbreviated as LLA.)

3.

Upper Level Applications: A group of subroutines that are written using combination of LLA, and which the user will actually be using. (Will be abbreviated as ULA.)

There are other subroutines for controlling the offset of coordinate axes and the linear offset of a coordinate system. Most quick plots of the coordinate axes can be made with ULA. If more advanced features are required for plotting the axes, the user may create an ULA for a more advanced purpose by combining the routines in LLA. In the following "explanation of subroutines," subroutines will be explained in the order of upper-level applications (ULA), UZPACK, and lower-level applications (LLA).

A user who wishes to plot simple coordinate axes may skip to Section 3.6 "The Explanation of Upper-Level Routines" after reading the explanation in the next section on "the Position of Coordinate Axes." These should be enough for plotting simple coordinate axes desired by the user.