Perturbation & Resummation
Courses
Asymptotic series, Padé/Borel resummation, and when divergent series still work.
Content for this course is still being written. For now, explore the skill map below — every node links to its full page.
Skill map
Each node is a skill; an arrow means "learn this first." Deep-dive links go to the full pages.
Divergence & Resurgence…
Factorially divergent series hide nonperturbative structure.
content coming soon
Padé Approximants…
Rational approximation reaches past the radius of convergence.
content coming soon
deep dive ↓Padé Approximants
Shanks / Wynn…
Nonlinear sequence acceleration removes leading error.
content coming soon
deep dive ↓Shanks Transformation and Wynn's ε-Algorithm
Borel Resummation…
Transform, Padé, integrate to resum a divergent series.
content coming soon
deep dive ↓Borel-Padé Resummation
WKB / Semiclassics…
Semiclassical quantization via the classical action.
content coming soon
deep dive ↓WKB and Semiclassical Methods
Variational Perturbation…
A trial parameter tamed by minimal sensitivity.
content coming soon
deep dive ↓Variational Perturbation Theory
Hyperasymptotics…
Exponentially small corrections refine the asymptotic series.
content coming soon
deep dive ↓Hyperasymptotics
Casida's Equation…
Linear-response electronic excitations.
content coming soon
deep dive ↓Casida's Equation