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  • Ferret Users Guide
    • Users Guide Index
    • Commands Reference
    • 1. Introduction
    • 2. Data Set Basics
    • 3. Variables & Expressions
    • 4. Grids & Regions
    • 5. Animations & Gif Images
    • 6. Customizing Plots
    • 7. Handling String Data Symbols
    • 8. Working with Special Data Sets
    • 9. Computing Environment
    • 10. Converting to NetCDF
    • 11. Writing External Functions
    • Glossary
    • Appendix A: Functions
    • Appendix B: PPLUS Guide
    • Appendix C: Ferret-Specific PPLUS Enhancements
  • Previous Release Notes
  • Tutorials and Demos
    • Ferret Tour
    • DSG files: Discrete Sampling Geometries Demo
    • Ferret sorting demo
    • Fast Fourier Transforms demo
    • Empirical Orthogonal Functions demo
    • Ferret objective analysis demo
    • Ferret Palette Demo
    • Map projections
    • Ferret polygon vector demo
    • Ferret Graticules demo
    • Ferret Polytube Demo
    • Ferret Polymark Demo
    • Ferret Constant-Array demo
    • Ferret land_detail demo
    • COADS Tour
    • Levitus Tour
    • Use OPeNDAP
    • Ferret binary read demo
  • PyFerret
    • PyFerret Downloads and Install ../../faq/ferret-faqs.html
    • What is PyFerret?
    • Why use PyFerret?
    • PyFerret for the Ferret user
    • PyFerret command syntax: quick-start notes
    • PyFerret for the Python user
    • Graphics in PyFerret ?
    • New Ferret functionality
    • PyFerret Python functions and constants
    • PyFerret Python objects and methods
    • Ferret external functions in Python
    • Ferret Fortran external functions
    • PyFerret metadata-and-data dictionaries
  • OPeNDAP
    • OPeNDAP usage in Ferret
    • Use OPeNDAP Demo
    • Test OPeNDAP

INTRODUCTION


Plot Plus (PPLUS) is an interactive, command-driven general-purpose program for plotting user supplied data. PPLUS recognizes data in standard Fortran formatted, unformatted and free format files as well as some specialized formats (see the section on Data Formats). Data can also be entered from the keyboard.

The major use of PPLUS is the plotting of contour data and X-Y pairs. A very small number of commands are required to generate a plot, making use of the many defaults available. However, it is also possible to control almost every aspect of the plot and to generate a final product which looks as though it were professionally drafted. Over thirty character sets are available, including special Greek and Math symbols. It is possible to make a composite of several plots of different kinds (or the same kind) on a single page and to add text information anywhere on the plot.

PPLUS commands can be entered interactively from the keyboard or from a command file much like a VAX/VMS command file. PPLUS command files support parameter passing, symbol substitution, and logic structures such as WHILE loops and block IF statements. The PPLUS command files are simple ASCII disk files which are easily edited with any VAX/VMS editor.

Interactive help is available with the VAX/VMS command HELP PPLUS. (First, PPLUS definitions must have been established as indicated in the Getting Started chapter.)