1 Introduction

PGPLOT is a high level graphics package for plotting X versus Y plots, functions, histograms, bar charts, contour maps and images. Complete diagrams can be produced with a minimal number of subroutine calls, but control over colour, lines-style, character font, etc,. is available if required. The package was written (by Dr T J Pearson of the Caltech astronomy department) with astronomical applications in mind and has become a de facto standard for graphics in astronomy world wide.

The package exists in two versions: the original or ‘Native’ version which uses the low level graphics package GRPCKG which was also written at Caltech, and a version developed by Starlink, in collaboration with Dr Pearson, which uses GKS. The two versions have identical subroutine interfaces and in most cases, applications can be moved from one version to the other simply by re-linking.

Starlink supports both the ‘Native’ version and the ‘Starlink’ version which co-exist on Starlink systems. Most packages available in the Starlink Software Collection currently use the Starlink version but work is currently underway to replace this with the Native version.

The current Native PGPLOT is version 5.2.0. The current Starlink PGPLOT is based on PGPLOT Version 5.1.1.

The main source of information on using PGPLOT is the PGPLOT manual. The manual for version 5 is still in preparation but a hypertext version can be found at:

http://astro.caltech.edu/\~tjp/pgplot/

This describes the original GRPCKG Native-PGPLOT version but the majority of the manual applies equally to both versions.

When using the GKS Starlink-PGPLOT version the following sections of the manual should be ignored and the information in this user note used instead: