This is the first thorough examination of weakly nonlocal solitary waves, which are just as important in applications as their classical counterparts. The book describes a class of waves that radiate away from the core of the disturbance but are nevertheless very long-lived nonlinear disturbances.

I Overview.- 1 Introduction.- II Analytical Methods.- 2 The Method of Multiple Scales and the E-Power Series.- 3 Hyperasymptotic Perturbation Theory.- 4 Matched Asymptotic Expansions in The Complex Plane.- 5 Stokes' Expansion, Resonance & Polycnoidal Waves.- 6 Theorems and Proofs: Existence Non-Existence & Symmetry.- III Numerical Methods.- 7 Pseudospectral and Galerkin Methods.- 8 Nonlinear Algebraic Equations.- 9 Special Algorithms for Exponentially Small Phenomena.- IV Applications.- 10 Water Waves: Fifth-Order Korteweg-Devries Equation.- 11 Rossby & Internal Gravity Waves: Nonlocal Higher Modes.- 12 The ?4 Breather.- 13 Envelope Solitary Waves: Third Order Nonlinear Schroedinger Equation and the Klein-Gordon Equation.- 14 Temporal Analogues: Separatrix Splitting &The Slow Manifold.- 15 Micropterons.- V Radiative Decay &Other Exponentially Small Phenomena.- 16 Radiative Decay Of Weakly Nonlocal Solitary Waves.- 17 Non-Soliton Exponentially Small Phenomena.- 18 The Future.- References.