Chapter 2

Introduction to IDL

2.1	Beginning an IDL Session
2.2	Basic Entities in IDL
	2.2.1 Data Types
	2.2.2 Variable Names
	2.2.3 Assignment of Values to Variables
	2.2.4 Commands
2.3	A Sampling of IDL Capabilities
	2.3.1 Creating and Examining Arrays
	2.3.2 Simple Mathematical Manipulations
	2.3.3 A Further Note on Array Indices; Matrix Multiplication
	2.3.4 Solving Linear Equations
	2.3.5 A First Graph
2.4	Saving and Retrieving the IDL Session
2.5	Loops, Logical Expressions, and Conditionals
2.6	Reading Data from a File
2.7	On-line Help
2.8	Pro-Files
2.9	Eigenvalues and Eigenvectors
2.10	Graphing Scalar Functions of One Variable
	2.10.1 The Basic Strategy
	2.10.2 Plotting Several Graphs on One Set of Axes
	2.10.3 Polar Plots and Custom Axes
	2.10.4 Multiple Plots On a Page
	2.10.5 Plotting Experimental Data
2.11	Making Hard Copy
	2.11.1 ... of Text
	2.11.2 ... of Graphs
2.12	Graphing Scalar Functions of Two Variables
	2.12.1 A Preliminary: The Procedure lugen_grid
	2.12.2 Surface Plots: The Procedure surface
	2.12.3 Contour Plots: The Procedure contour
	2.12.4 Shaded Surfaces: The Procedure shade_surf
	2.12.5 The Procedure xsurface
	2.12.6 The Procedure show3
	2.12.7 Functions of Two Variables in Polar Coordinates
2.13	Graphing Scalar Functions of Three Variables
	2.13.1 Reduction to Two-Dimensional Displays
	2.13.2 Isosurfaces
	2.13.3 Other IDL Routines
2.14	Graphing Vector Fields
	2.14.1 The Procedure velovect
	2.14.2 The Procedure vel
	2.14.3 The Procedure plot_field
	2.14.4 More Elaborate Displays
	2.14.5 Three-Dimensional Vector Fields
2.15	Animation
2.16	Advanced Graphing Features
	2.16.1 Fonts
	2.16.2 Space Curves
	2.16.3 System Variables
	2.16.4 Using Multiple Windows
	2.16.5 Scaling so Circles are Circles
	2.16.6 Working with Color
2.17	Miscellaneous Occasionally Useful Tidbits
2.18	References
2.19	Exercises
	2.19.1 Writing IDL Statements
	2.19.2 Finding Eigenvalues and Eigenvectors
	2.19.3 Graphing Scalar Functions of a Single Variable
	2.19.4 Graphing Scalar Functions of Two Variables
	2.19.5 Graphing Scalar Functions of Three Variables
	2.19.6 Graphing Vector Fields
	2.19.7 Animations
2.A	Listing of lugen_grid