Spivak's Calculus formalized in Lean 4

A comprehensive formalization of every theorem and problem from all 30 chapters and 9 appendices of Michael Spivak's Calculus, 3rd and 4th editions, implemented in the Lean 4 proof assistant. This project meticulously reproduces the formal mathematics for independent study, theorem verification, and proof exploration, serving as a resource for mathematicians and formal methods developers.