Contents

• Preface
• Acknowledgments
• An N-Body Code
• First Attempt
• Driver
• Input
• N-Body Integrators
• Inspecting the Leapfrog
• Acceleration
• Newtonian Gravity
• A Matter of Taste
• Potential Energy
• Local Arrays
• Energy Diagnostics
• Testing the N-body Code
• A 2-Body System
• A Bug
• The Simplest Case
• A Variation
• Another Variation
• Two Variations
• A single Time Step
• Debugging the N-body Code
• Forward Euler
• Nothing Wrong
• Two Possibilities
• Back to Square One
• A Warning Light
• Hindsight
• Bug Fixed
• One More Check
• A Single-Links Version
• A Figure-8 Triple
• Switching Places
• Single Links in +Body+
• Single Links in +Nbody+
• The DRY Principle
• Simplifying Further
• Finishing the Revision
• Two Tests
• Returning to Simplicity
• Extra +Body+ Variables
• Alternatives
• Forward
• Clean Code
• Sending a String
• Wishful Thinking
• Implementation
• Indirect String Sending
• The Same, Yet Different
• Testing
• A Final Version
• Clarity
• Brevity
• Correctness
• More Information
• An Initial Snapshot Output
• A New Driver
• A Final Test
• An Eight-Body System
• Setting Up a Cube
• Letting Go
• Passing Through
• Convergence
• Softening
• Close Encounters
• Fuzzy-Point Particles
• A New Driver
• A Code with Softening
• Details
• Cold Collapse with Softening
• Check
• Large Softening
• Even larger softening
• Small Softening
• Central Collapse
• Literature References